Crushed Peas with Feta and Scallions

This is a lovely dish to serve with grilled pita bread, either alongside a couple of other mezze, while you have a drink before supper, or as an appetizer in its own right, or as a light lunch with a good salad on the side. In the summer, please use fresh peas; at all other times of year the wondrous frozen pea will do. You can make this dish in advance, put it in the fridge, and bring it back to room temperature when you want it.