Beef Stroganoff Sandwich   2 pounds ground beef 1/2 cup chopped onion 1 teaspoon salt 1/2 teaspoon garlic powder 1/2 teaspoon pepper 1 loaf french bread Butter or margarine, softened 2 cups (16 ounces) sour cream 2 tomatoes, seeded and diced 1 large green pepper, diced 3 cups (12 ounces) shredded cheddar cheese   In a skillet, brown ground beef and onion. Drain. Add salt, garlic powder and pepper. Cut bread lengthwise in half; butter both halves and place on baking sheets. Remove meat mixture from the heat; stir in sour cream. Spoon onto the bread. Sprinkle with tomatoes, green pepper and cheese. Bake at 350 degrees for 20 minutes or until the cheese is melted (bake longer for crispier bread). Yield: 8 - 10 servings.