2,798. Things That Require Clarification
Hilchos Nedarim 9:6
In a place where a person’s agent would have to ask for clarification, the thing is considered in the category of what the person mentioned generically. For example, imagine a place where a person sends an agent to buy meat generically, and the agent tells him that he could only find fish. In such a place, one who vowed not to eat meat may not eat fish either. The same is true in all comparable situations. In any place, one who vows not to eat meat is also prohibited to eat poultry and entrails, but he is permitted to eat kosher grasshoppers. [Note: the current practice of Ashkenazic Jewry is not to eat grasshoppers.] If it seems that when he took the vow he only intended to prohibit animal meat, or animal meat and poultry, then he is permitted to eat fish even in a place where an agent would ask for clarification.
Hilchos Nedarim 9:7
If someone takes a vow not to eat cooked food, he may still eat a soft-boiled egg. If he vows not to eat food that was boiled lightly in a pot, he is only prohibited foods that are boiled in a pot, such as buckwheat, dumplings, etc. If he prohibited himself anything that is put in a pot, then he may not eat anything cooked in a pot.