Terumos 10:1

If one put a whole onion into lentils (and one is terumah while the other is chullin), non-kohanim may eat the chullin (because an uncut onion does not facilitate an exchange of flavors). If the onion is cut up, non-kohanim may not eat the chullin because of the exchange of flavors. Rabbi Yehuda permits a non-kohein to eat pickled fish in which an uncut terumah onion had been placed because that is only done to remove the unpleasant odor.

Terumos 10:2

If an apple of terumah was grated into chullin dough that then leavened, it is prohibited to non-kohanim. If barley of terumah fell into a well, the water is permitted to non-kohanim even though it absorbed flavor (because the flavor of the barley does not enhance the taste of the water).