Butternut Squash Salad with Sour Grapes

A very Persian salad. Well, it would be if not for the fact that for most Persians salad is just tomato, cucumber and onion. What I mean is that the flavour is quintessentially Iranian, comprising fragrant spices, split peas, and verjuice. Verjuice (verjus, or ab ghooreh in Farsi) has been prepared for centuries as a way of using fruit deemed too sour for other purposes. It can be made from crab apples, but in the Middle East it is usually made from tiny sour grapes. It is som