Challah, Chapter 1, Mishnah 5. This mishnah continues to discuss which items are obligated in, or exempt from, the mitzvah of challah.
"Isah shetechilatah sufganin vesofah sufganin - peturah min hachallah" - Dough whose beginning is sufganin and whose end is sufganin is exempt from challah:
Sufganin is a loose batter rather than dough. When the mixture was a batter from the start, and its end was also as sufganin - meaning that it was fried in oil or in honey, or boiled in water - it is exempt from challah. Even though it hardens after the boiling or the frying, that is not enough to obligate it.
"Techilatah isah vesofah sufganin, techilatah sufganin vesofah isah - chayavin bachallah" - If its beginning is dough and its end is sufganin, or its beginning is sufganin and its end is dough, they are obligated in challah:
Its beginning is dough and its end is sufganin: At the start it was a dough and not a batter, and at the end it was boiled in oil, in honey or in water.
Its beginning is sufganin and its end is dough: At the start it was a batter, and in the end it was baked in an oven.
Both of these cases are obligated in challah because at some stage of the process they had the status of dough: either they are considered dough at the end, since they were baked in an oven, or they were a form of dough at the beginning, even though in the end they were not baked in an oven but boiled. Since at some point in the process there was a hardened substance of dough here, they are obligated in challah.
"Vechen hakenuvika'ot chayavot" - And likewise the kenuvika'ot are obligated:
These too are obligated. This refers to bread that has already been baked and was then ground until it became a sort of flour, similar to our matzah meal. If one then takes this flour and makes dough from it, the dough is obligated in challah.
In summary: In this mishnah we learned that the determining factor for the obligation of challah is the existence of a dough stage in the process: whatever begins as sufganin and ends as sufganin is exempt, while whatever begins as dough or ends as dough is obligated, and likewise the kenuvika'ot are obligated.