Mix together sugar, poppy seed, mayonnaise, milk and vinegar to form dressing. Toss together lettuce, onion and strawberries. Add dressing immediately before serving.
About 1 hour before serving ... the mayonnaise, salt, vinegar, onion, mustard, pepper and 1/4 cup milk. Stir in potatoes and ... salad immediately on lettuce leaves or cover and refrigerate to serve later. Makes 6 servings.