Pare cucumbers. Cut slice from each end. Cut cucumbers in halves crosswise. Scoop out the centers, making thin-shelled cups. Chill thoroughly. Combine cucumber pulp, peas, and chicken. Season to taste. Moisten with mayonnaise. Mix lightly with 2 forks. Fill cucumber cups with the mixture. Stand each cup on a slice of tomato which rests on a bed of lettuce. Serve with mayonnaise. Garnish with paprika. 6 servings.