 In the past, the Sabbath-observant would leave their food heating on the stove where it had been covered with a blech (metal sheet), or in the oven in which had been cooked before the onset of Sabbath.Contemporary consumers seek to use their kitchen’s oven to keep food hot for Sabbath consumption but must be assured that in opening the door to retrieve food, no Sabbath laws will be inadvertently contravened.On weekday holidays (Yom Tov), food may be cooked, but turning the heat on is prohibited.