Tomato Egg Salad

In a medium saucepan, cover eggs with water. Bring to a boil over high heat. Remove from heat; cover and let stand 12 minutes. Drain, rinse, peel and chop cooked eggs.
Meanwhile halve tomatoes lengthwise and remove seeds. In a mixing bowl combine cucumber, onion, mayonnaise, mustard, salt and pepper. Fold in chopped egg.
Divide greens among 4 plates. Top each with 3 tomato halves; spoon on egg salad. Drizzle with any remaining dressing. Makes 4 servings.