All-purpose dressing

This is the one I use most often because it’s as suited to leaf salads as to those mixed-up salads using odds and ends from the fridge that can be so good – quartered small potatoes, broccoli or cauliflower florets, black olives, capers, bits of cooked pasta, sliced cos lettuce, chunky granary bread croutons, chopped toasted nuts, and so on.