In a large bowl, combine green beans, corn, onion, and green bell pepper. Stir in sour cream, condensed soup, and shredded cheese. Season with salt and pepper. Mix well, and spread into a 2 quart casserole dish. In a separate bowl, mix together the crushed crackers and melted butter. Sprinkle over vegetable mixture.
Bake in preheated oven, for 25 minutes, or until the top is golden brown.