Simmer whole quinces in a covered saucepan with about 1 in. water until a knife slides right in, about 50 minutes. Quarter fruit, core, and slip off peels.
Purée quince flesh in a food processor, adding the cooking liquid plus enough more water for a looser texture. Then add lemon juice and a little sugar to taste to heighten the flavor. Enjoy it by the bowlful, or spooned over pork chops.