This is delicious! Lemon enhances the flavor of quince. This year I plan to try it with orange and grapefruit (for which I will have to freeze quinces until citrus is in season). If you like you can put the peels and cores of the quinces in a cheesecloth bag and add to the ingredients in the saucepan. This will really thicken the marmalade, all that pectin in the peels and cores. I make several jars and freeze them, but you could also can them in a water bath. Follow the manufacturer’s directions for canning.
4 c peeled, cored, chopped quince
1/2 lemon, seeded and coarsely chopped
1 1/2 – 2 c sugar
2 c water
1 piece, about 1″ (or more) vanilla bean; or 1 t vanilla extract
1. Put chopped quince and seeded lemon pieces into a food processor and finely chop. Or chop by hand as finely as you can.
2. Transfer to a heavy-bottomed saucepan and add remaining ingredients. Bring just to the boil, then reduce heat and simmer, stirring occasionally, until the mixture has thickened and has reduced to about 3 1/2 cups (just guestimate this amount), about 50 minutes or so.
3. Cool some then transfer to clean, preferably sterile jars and refrigerate, freeze, or can, as is your wont. In the fridge it should keep a good while, several months.