Serves 4 to 6.
Whisk first 3 ingredients together in small bowl. Stir in dill. Season generously with salt and pepper.
If using fresh peas, steam until tender, about 3 minutes. Do not precook frozen peas. Transfer peas to bowl. Steam potatoes over boiling water until tender, about 15 minutes. Cool completely. Add to peas. Add all remaining ingredients to peas. (Can be made 6 hours ahead. Cover and chill.) Toss salad with dressing. Season to taste with salt and pepper.