Even those of us who have kept Shabbat our whole lives may not be too familiar with the details of how the kitchen is to be prepared before this sacred day of rest, when we refrain from many activities.

The Shabbat laws center around the 39 melachot (creative activities) that we avoid. Throughout this article, we’ll be referencing which malachot are at play and how they are best avoided.

Ready? Let’s go!

Precut Paper Towel and Aluminum Foil

You should precut any paper towels and aluminum foil that you might need on Shabbat.

Why Do We Do This?

Ripping paper towels or aluminum foil is not allowed on Shabbat (whether you tear along the perforated lines or in between them), as it can fall under the category of koraya (tearing), mechatech (cutting to measure), and/or makeh b’patish (finishing touches that prepare an item for use).1

Bottom Line

Be sure to cut (or buy pre-cut) paper towels and aluminum foil in advance of Shabbat.

Open Cans You’ll Need for Shabbat

Ideally, before Shabbat, open any cans you’ll need on Shabbat.

Why Do We Do This?

We don’t want to create a useful container, due to the prohibition of makeh b’patish, applying the finishing touches to the formation of a utensil. Some halachic authorities say that opening a can falls into this category.2

Bottom Line

If you didn’t open the cans before Shabbat, the key is to open them in a way that doesn’t create a useful container. Here are two common techniques:

  • Some halachic authorities suggest puncturing the bottom of the can and only then opening the top. This prevents the container from becoming a useful receptacle. (If using this technique, be sure to have another container handy to catch the liquids that will spill from the can.)3 Others, however, are of the opinion that this suggestion would only help if it’s a flimsy, non-reusable receptacle to begin with.4
  • Another option is to leave the top of the can partly attached. If you have a sharp, protruding top, you won’t be able to use the can in a safe manner, making it an "unworthy" vessel.5

Precutting Salads

Before Shabbat, grind, grate, or finely dice any fruits and vegetables you plan to use on Shabbat. (There’s no problem with cutting them into larger pieces on Shabbat itself.)

Why do we do this?

On Shabbat, you can’t grind, grate, or finely dice fruits and vegetables. This can be a violation of the melachah of tochain, grinding6 (see footnote regarding mashing foods like eggs that don’t grow from the ground7).

Now, if the food is chopped to a size that’s larger than what it’s usually cut to during the week, or, according to some authorities, as long as it’s still too large to swallow as is, it’s not considered ground. But this can vary by food.8

Bottom Line

To play it safe, if you want to have finely chopped veggies in your salad, do the cutting in advance.

(Note: It’s halachically problematic to eat completely peeled onions or garlic that were left overnight, even in a sealed bag, unless they still have their roots attached [i.e., the hair at the head of the garlic and onion]. However, you can mix cut-up onion and garlic with other foods.)

On Shabbat itself, if you want to crush something (for example, avocado for guacamole), you can do so only under the following conditions:9

  1. Use a shinui, which means you should crush the food in an irregular manner (e.g., using a spoon, knife, or spatula). Avoid using the most appropriate tools like a grinder, potato masher or fork.
  2. Prepare the dish right before you plan to eat it.
  3. Ensure that the pieces are larger than the usual size. If you intended for the pieces to be somewhat larger than usual but they ended up smaller, it’s OK.

Pickling and Dressing Salads

Some salads need to be dressed before Shabbat since their dressing can be considered a form of pickling, especially if you use a lot of vinegar or another acidic dressing and let the salad sit for a while.

Why Do We Do This?

There are two reasons suggested as to why pickling is prohibited on Shabbat:10

  • Pickling achieves a similar effect to cooking, so some say it’s considered a form of cooking.
  • Others liken pickling to tanning hide (in which strong chemicals modify the material).

Bottom Line

Halachah considers “pickling” to occur when a vegetable is either soaked in any liquid for 24 hours, or in vinegar or strong acidic liquids for merely 18 minutes.11 So unless you plan to use a mild dressing or dress your salad in a bit of vinegar right before eating it, do it before Shabbat.12

Mixing Mayo Into Tuna and Eggs Salad

If you plan to serve tuna or egg salad, it’s ideal to mix in the mayo before Shabbat.

Why Are We Doing This?

Kneading dough (losh) is one of the 39 melachot. Adding mayo to fish or eggs and mashing it into a homogeneous mixture is similar to mixing flour and water to make dough.13

Bottom Line

Some teach that this is an issue and therefore advise that this be done before Shabbat.

If you didn’t have a chance to make your tuna or egg salad before Shabbat, some halachic authorities say you can do so in an “irregular” way. For example, you can put the mayo in the bowl before adding the tuna or eggs, and then, using a spoon, mix back and forth instead of in a circular motion (preferably lifting the spoon between each stir).14 Other authorities, however, are of the opinion that this solution would only help for foods that would remain “runny,” but not for something like egg or tuna salad.15

Note that the concern here is that you’re making a mixture that resembles dough. If the pieces are chunky and don’t become a single mass, you can mix in mayo exactly as you’d do all week.

Disabling Automatic Lights

Many refrigerators have a light that gets switched on when they’re opened and off when closed, which is problematic on Shabbat.

Some newer models of refrigerators come with a built-in Shabbat-mode override, and all you need to do is turn it on before Shabbat.

With older models, you can either unscrew the bulb or tape down the button so that the light stays off (in some models, a magnet over the sensor may also work).

A similar problem exists with auto-defrost freezers, which have fans that are activated whenever the freezer door is opened. So take steps similar to the above to avoid indirectly switching on the fan on Shabbat.

Setting the Cholent (Hameen) to Stew

It’s customary to eat a warm dish that started cooking before Shabbat began and continued to cook until Shabbat day. This tradition both enhances our Shabbat enjoyment and supports the sages’ explanation of the verse “You shall not burn a fire in all your dwellings on the Sabbath day.”16 The sages say this refers to a fire lit on Shabbat itself, but you can leave a fire that was lit before Shabbat burning on Shabbat itself (so you can have warm food, as well as lights and warmth in the house).17

How is this done?

Blech: Covering the Fire

One way to keep food warm over Shabbat is to put a metal sheet called a blech (Yiddish for “tin”) over your burners, turn the burners to low, and leave a pot of stew on the stove to simmer throughout Shabbat.

A blech is not always necessary. But there are certain instances when you might be tempted to adjust the fire (or heat source), so the sages said you need to have a reminder in place. This used to entail covering or removing the coals; nowadays, this is achieved by covering the burners (and knobs18).19

The blech is needed in either of the following two scenarios:

  • The food is only partially cooked when Shabbat comes in (or it’s fully cooked, but the taste will improve the longer it sits on the fire).20
  • The plan is to remove the food from the fire and then put it back onto the fire shortly thereafter21 (which you might do if you want to serve some of the food now and keep some of it hot for later).

You shouldn’t remove food from a pot while it is still on the fire, since the inadvertent movement of the food during this process is a form of "stirring," which may cause some of the food to cook more.22

So the solution would be to remove the pot, ladle out the food, and then put it back.

It goes without saying that partially cooked food cannot be put back on the flame on Shabbat, as that constitutes bona fide cooking. Even if it’s fully cooked, the sages prohibited returning it to the flame, as it might appear like cooking. The use of a blech helps address this concern by ensuring the pot is no longer placed directly on the flame.23

The Crockpot

A Crockpot is another way to keep food warm over Shabbat. You can make a blech by covering the inside heating elements with foil. Ideally, cover the knobs as well, as that reminds you not to adjust the heat.

Wrapping Food (Hatmanah)

Aside from the prohibition of cooking on Shabbat, there is a related rabbinic prohibition of hatmanah, or “insulating.” This involves the prohibition of wrapping hot or warm foods on all sides in a way that retains the food's heat. There is, however, a difference between hatmanah before and on Shabbat.24

Before Shabbat, hatmanah is only forbidden if the insulation also causes the food to become hotter, like wrapping it in extra layers of foil before placing it in a preheated oven, since the food is both insulated and there is a source of heat.

You may, however, wrap a pot of soup in a towel right before Shabbat, since it won’t make the soup become any hotter than it is already.

On Shabbat itself, you can’t insulate the food, even when there is nothing that will cause the food to become hotter.

Now, a Crockpot typically surrounds the pot on all sides quite snugly. So is this considered forbidden hatmanah?

Some say it is (plus it “looks like cooking”) and remedy this by putting a ball of foil between the pot and the heating element.25

Others are of the opinion that it’s not an issue since the top of the pot is not insulated, and hatmanah applies only if something is wrapped on all sides.26

Please note: There are very specific instructions and conditions regarding removing and returning a pot to the fire on Shabbat.

For more on this, see Food Preparation on Shabbat.

Leaving Food in Ovens

Opening and closing an oven on Shabbat poses a number of potential problems.

  • Doing so may trigger a light, which you’d need to deal with the same ways discussed above regarding refrigerators.
  • You can’t open a thermostatically controlled oven on Shabbat, since it may either cause the heat source to be turned on or be increased.

So if you plan on leaving your oven on and opening the door on Shabbat, you’d need to disable the thermostat before Shabbat. (Once it’s completely disabled, the oven door may be opened even if the heat source is in operation. But you must be certain that the thermostat was indeed disabled.)

Note: This only helps you to take out food that was already cooked and in the oven before Shabbat. You may not, however, put any food into the oven on Shabbat itself.

Also note that all of this applies even if you set the oven on “Sabbath mode,” which is actually a misnomer and is useful on Yom Tov but not at all on Shabbat.

Seems like a lot to keep track of? Many have found that creating a weekly checklist is a great idea. It helps you stay organized and ensures everything is set before Shabbat arrives.