Caterina Silva, chef and teacher at Kiss the Cook culinary school, first told me about this wonderful way of serving cooking apples: it’s sour, sharp, rich and sweet, all at once. Quince trees are common in Portugal, and the fruit is usually cooked or preserved in jam or in a firmly set paste called marmelada. In English this is sometimes known as quince cheese, or by its Spanish name, membrillo, where it is served alongside salty cheeses. It’s easy to find in delicatessens or online and keeps very well in the fridge.