How to Prepare Food in a Non-Kosher Kitchen

BAKING IN NON-KOSHER OVEN

An oven that has not been used for at least 24 hours is considered, d'oraita, to be neutral/pareve, but only if it is clean. D'rabanan, it is still not kosher, but this may be useful for when you can be lenient; e.g., if there is a safek.

Note Even when baking in a non-kosher oven, you must cook the food in a kosher utensil.

INTRODUCTION TO BAKING IN NON-KOSHER OVEN

Baking in a Non-Kosher Oven

How To Tell if Oven Is Clean

To determine whether a non-kosher oven with black or brown spots is clean, scratch them:

  • If the substance crumbles, the spots are OK and you may bake non-liquid food in that oven without covering the food.
  • If the spots do not crumble or they remain immovable or come off in flakes rather than crumbles, consider the oven not clean.

Uncovered Food; Clean (Non-Kosher) Oven

You may cook food uncovered in a non-kosher oven if:
  • The oven rack and walls are clean, and
  • The food is not “liquid.”
    Note Non-liquid is defined as not being liquid before cooking OR not being liquid after cooking, but the food does not need to be non-liquid at both times.  Examples of “non-liquid” foods:
    • Apple cobbler
    • Lasagna
    • Meat (that will create gravy at the end)
    • Pudding
    • Raw fish.
Situation You plan to bake uncovered food in a clean, non-kosher oven in which the racks are not clean.
What To DoPlace two layers of foil under the baking utensil.

Double Wrapping

When To Double Wrap

Double-wrap food before baking in a non-kosher radiant-heat oven if:
  • The rack and/or oven are not clean;
  • The food that you are baking is liquid at any time during the cooking process; OR
  • Some of the food you are baking spills onto the rack or oven surfaces.

How To Double Wrap

When wrapping food for cooking in a non-kosher oven, the wrapping material does not need to seal completely, but the:

  • Food must be completely covered with two layers of foil or plastic;
  • Layers must keep water vapor out from between the layers; and
  • Surfaces of the utensil must all be covered.

SPILLED KOSHER FOOD IN NON-KOSHER OVEN

Kosher Food Spilling in Non-Kosher Oven

If kosher food spills inside a non-kosher oven in which you are cooking uncovered kosher food (whether liquid or non-liquid), consult a rabbi about whether the uncovered kosher food may still be eaten.

NoteIn this case, it makes no difference whether the oven is clean or dirty because the spilled food is wet and takes on the non-kosher status of the oven. When the spilled food vaporizes, it carries the non-kosher essence to the kosher food or utensil.
NoteIf the non-kosher oven had not been used for more than 24 hours, the food is probably still kosher b'di'avad. 
NoteThis applies to food spilled either from the same utensil in which you were cooking the kosher food or from a different utensil.

FROZEN FOOD IN NON-KOSHER OVEN

Double Wrap Frozen Food in Non-Kosher Oven

Frozen food is considered to be wet food regarding cooking it in a non-kosher oven or regarding its being neutral for dairy and meat issues: If the oven is not kosher, the frozen food must be double wrapped, even if the oven is clean.

AIRLINE MEALS IN NON-KOSHER OVEN

Heating Airline Meals in Non-Kosher Oven

Airline meals are usually non-liquid, so even if they are single-wrapped, it is OK to heat them in a non-kosher oven as long as no non-kosher food contacts the kosher food container.

COOKING IN NON-KOSHER MICROWAVE OVEN

Microwave Oven: Kosher Status

Introduction to Microwave Oven: Kosher Status

If a microwave oven's walls/floor/door do not become hot (more than 120° F, or 49° C), the microwave oven does not become non-kosher, dairy, meat, or non-Passover/chametz.

NoteA microwave oven that does not normally get hot, may get hotter than 120° F if you cook:

  • A liquid or moist food for a long time (even if less than 10 minutes),
  • Several liquid or moist items sequentially, or
  • Popcorn and similar foods.

If a microwave oven's walls/floor/door get hot, the oven can become dairy, meat, or non-kosher (if they become one gender and then the opposite gender is cooked or if non-kosher food has been cooked in it). If any surface--including walls, door, floor, etc.--that gets hot are plastic or coated metal, it cannot be returned to kosher or pareve. However, if the surfaces are all made of metal, they may be kasherable. Consult a rabbi.

NoteIf the microwave oven does get hot, it cannot be kashered at all--not for Passover and not from non-kosher to kosher. To check if your microwave oven gets hot, see How To Check If a Microwave Oven Will Get Hot during Cooking

Microwave Oven: Kosher Status: Walls and Door

Since microwave oven walls and doors do not normally get hot (more than 120° F, or 49° C), there is usually no need to kasher them from milk to meat (or back to milk); from ordinary use to Passover use; or from non-kosher to kosher. Just clean all surfaces.

Microwave Oven: Kosher Status: Floor

Microwave oven floors can get hot, especially where there is no rotating glass tray and the utensil is placed directly on the oven floor. All microwave ovens should be assumed to get hot unless you have tested them personally.

Microwave Floor

Cover the floor (ideally with styrofoam or another substance that blocks heat and moisture) in a non-kosher microwave oven.

Glass Tray

The glass tray does not become non-kosher and does not become dairy or meat or chametz (unless it was removed and used in a conventional oven) as long as it is clean.

Plastic Tray Support

The plastic support under the glass tray must be cleaned and must be blocked from contact with actual cooking utensils and from food if the tray:

  • Has any food of the gender opposite that of the food being cooked,
  • Has non-kosher food on it, or
  • Is dirty and you cannot tell with what.

How To Check If a Microwave Oven Will Get Hot during Cooking

To determine if the walls of a microwave oven will get hot during cooking:

  • Boil water for as long as food would typically be cooked in that microwave oven, and
  • Touch the inside walls, floor, door, and ceiling
    • If the walls are too hot to touch, the walls may acquire the gender of any food cooked in the oven. (If the walls are already the opposite gender when cooking a food, the oven may become non-kosher.)
    • If the walls are not too hot to touch, then no change of status occurs.

Non-Kosher Microwave Oven: Hot Oven, Liquid or Solid Food

If the walls of a non-kosher microwave oven get hotter than 120° F, you must double wrap any liquid or solid food you cook in that oven.

NoteIf you did not double wrap liquid or solid food cooked in a non-kosher microwave oven, consult a rabbi about whether you may eat the food.

Non-Kosher Microwave Oven: Non-Hot Oven

If the walls of a non-kosher microwave oven stay less than 120° F, you do not need to wrap or cover liquid or non-liquid food, as long as:

  1. The microwave oven is clean and dry, and
  2. If the tray is non-glass or non-Pyrex, you put a layer of separation (plastic, styrofoam, etc…) that blocks heat and any moisture underneath the cooking utensil.

COOKING ON NON-KOSHER STOVE

Setting Down Hot Lid on Non-Kosher Stove Top

SituationYou set down a hot pot lid on a non-kosher stove top.
Status

  • Lid is dry and stove is clean: lid remains kosher.
  • Lid is dry or wet and stove is dirty: lid is non-kosher.
  • Lid is wet and stove had hot non-kosher mixtures on it within the previous 24 hours--even if the stove is clean: lid is not kosher.
  • Lid is dry or wet and stove is clean and did not have hot non-kosher mixtures on it within the previous 24 hours: lid is kosher.

COOKING WITH NON-KOSHER UTENSILS

Using a Non-Kosher Kitchen Utensil
Introduction to Using a Non-Kosher Cooking Utensil
You may not use a non-kosher cooking utensil (pot, pan, baking dish, etc.) for cooking even if the utensil is clean and has not been used for more than 24 hours (unless you kasher it first).

Fruit Cut with Non-Kosher Knife
You should wash most fresh fruit cut with a non-kosher knife in order to remove whatever non-kosher food might have been on the knife from before.
Note Fruit with a sharp taste—such as lemons or tart apples—may not be used if cut with a non-kosher knife, regardless of whether the knife had been used within 24 hours.

WASHING IN NON-KOSHER SINK

Using a Non-Kosher Sink
A dish is still kosher b'di'avad if heated to 120° F (49° C) or more in a clean, non-kosher sink that had remained below 120° F for the previous 24 hours.