Nedarim, Chapter Six, Mishnah Two
This mishnah deals with a person who vows not to eat food which goes into a pot. The mishnah relates to two such types of food; 1) food that is totally boiled in the pot; 2) food that is lightly cooked in a pot and is finished cooking somewhere else, such as in a frying pan or in an oven.
1) He who vows abstinence from food prepared in a pot, is forbidden only from food boiled in a pot;
2) But if he says, Konam that I taste whatever goes down into a pot, he is forbidden everything prepared in a pot.
Section one: If a person takes a vow forbidding himself from eating anything prepared in a pot he is only forbidden from eating things totally prepared in the pot, meaning that they were completely boiled in the pot. An example would be a grain dish, which in Talmudic times was boiled in water. He would still be permitted to eat things which had preliminary stages of their cooking in a pot and were later baked or fried.
Section two: However, if he says whatever goes down into a pot, he is forbidden to eat anything that has at any time been in a pot.