Wash the lettuce and other vegetables thoroughly. When preparing the lettuce, use only the green part of the leaves and cut out the vein at the base of the leaves before chopping. Peel the cucumber before dicing. Cut the bell peppers into large chunks. Dice only the green stems of the onions. Julienne the carrots. Seed and dice the tomato (this will not be tossed with the other ingredients). After preparing the vegetables, keep the tomato and sunflower seeds to the side and toss all the rest of the vegetables together into a large bowl. Serve with the sunflower seeds, tomato, and Ranch dressing or a dressing of your choice.