Nedarim, Chapter 6, Mishnah 1. This chapter deals with the question of what is included in a person's vow when he specifies a particular item, and especially a particular type of food: what falls within that vow and what remains outside it.
"HaNoder Min HaMevushal":
One who vows against cooked food - "Mutar B'tzli Uv'shaluk" - he is permitted to eat roasted food or food that is shaluk (meaning cooked far beyond the normal point, extreme cooking). Only ordinary cooking is included in his vow, while the other methods of preparing food, roasting and over-boiling, are not included in it.
"Konam Tavshil She'eini To'em":
One who vows in this language means not to taste any cooked dish. Although the word tavshil derives from the root meaning "to cook," in this context our Sages understood it to refer to a cooked food that is eaten together with bread, and it is by this definition that the scope of the prohibition is determined:
He is forbidden to eat a soft pot-cooked dish - anything cooked in a pot that is soft becomes forbidden to him, because a food of this sort is eaten together with bread.
He is permitted to eat a firm item cooked in a pot - since such a food is not normally eaten together with bread.
"UMutar B'beitzah Termita" - a particular type of cooked egg, which likewise was not normally eaten together with bread.
"Uv'dla'as HaRemutzah" - a gourd that was roasted in hot ashes, which also is not eaten together with bread.
In summary: one who says "tavshil she'eini to'em" does not include these items in his vow, since the vow applies only to foods that are eaten together with bread.