Is there any problem in doing the following on shabbat? Pouring cold store-bought humus onto a plate and then putting on top of that hot/warm mince meat that had been kept warm on an electric hot plate? Would there be a problem of cooking the humus?
This is an interesting point. There would be a problem with putting the hot meat on the chummus. Although the chumus itself is already cooked, and therefore in this instance would not get re-cooked by placing the meat on it, however there are spices i.e. garlic, pepper that aren’t and they would get cooked by the meat. This is similar to pouring hot water on to instant soup mixes that have parts that are precooked and spices that aren’t.
Igros Moshe O:CH 4-74 Bishul – 5.