Is it okay to use disposable aluminum pans without tevila to cook two parts of a meal? Or is that re-using? For example, if one is cooking eggs with vegetables, would it be ok to cook the vegetables and then add the eggs, or would they need to be in different pans? Or if one cooks pasta and leaves it in the pan and adds sauce to heat and mix all together? thank you–this is new to me.
According to the poskim who say that disposable aluminum pans do not need tevila, it is because the pan is not really meant to serve the person for a long time, rather it is used very briefly, and then thrown out. Therefore, it isn’t considered a “utensil” to be obligated in tevila. According to these poskim (which is the prevalent minhag in the U.S.A.) even if it was used another time or two, it is still not enough to consider it a real “utensil”, rather a throw away item. In your instance when it is being used for the very same meal that would all be considered one use.
As a side point, there is a misunderstanding among many people, that it is permitted to use a utensil once before toveling it. This is not true. A metal pot, which needs tevila may not be used even once before it is toveled.
Igros Moshe Y:D 3-23.