For someone (agent muɴ-) to cook food, mihda, a'an (theme i-), in a particular container (loc ref -an), by boiling in a pot, frying, pulītu, or roasting, hanglag.
Immuy nunhāang hi lapnay han babāi ta way onon tu'u.
The woman went to cook some sweet potatoes so we would have something to eat.
Reference is to the cooking process; a resultant state of being cooked is not implied.
Nan lapnay, ya nihāang mu agguy nalūtu.
As for the sweet potatoes, they have been cooked but they are not well-done.
The expected result of this process is for food to be well-done, lūtu.