Nedarim, chapter 6, mishnah 2. This mishnah deals with two wordings of a vow relating to food cooked in a pot, and teaches how the precise language of the vow determines the scope of the prohibition.
The first wording - "hanoder mima'aseh kedeirah":
One who vows against something made in a kedeirah, that is, in a pot used for boiling - "ein asur ela mima'aseh rechatta" - is forbidden only in food that was made entirely in the pot. Foods prepared in an ilpas, which is a kind of pan used for frying, are not included in the vow; and even something that began in the pot and was finished in the ilpas is not forbidden.
The second wording - "konam hayored lakedeirah":
But if he said "konam hayored lakedeirah," meaning that he vowed against anything that goes into the pot and did not use the wording "ma'aseh kedeirah" - "asur bechol hamitbashel bakedeirah" - he is forbidden in everything cooked in the pot. Even if the cooking process was completed in an ilpas, in a pan, the food is forbidden, because the expression "hayored lakedeirah" is broader and more inclusive.
In summary: the scope of the prohibition is determined by the precise language the person used - "ma'aseh kedeirah" forbids only ma'aseh rechatta, food made entirely in the pot, whereas "hayored lakedeirah" forbids everything cooked in the pot, even if its cooking was finished in an ilpas.