In a skillet, saute ham, onion and green peppers over moderate heat until vegetables are translucent. Meanwhile, in a small bowl, beat together eggs, water and salt. Pour egg mixture over cooked vegetables in skillet. Cook over low heat until eggs are almost set. Turn over and cook on other side. Cut into four wedges. Toast bread slices. Butter each slice. Top 1 slice of toast with 1 omelette wedge and half of the sliced tomatoes. Cover with another slice of toast. Cover the second slice of toast with half of the lettuce and a second omelette wedge. Top with third layer of toast. Cut sandwiches into four triangles and secure with toothpicks. Repeat for second sandwich.