Heat oil in a medium saucepan over medium-high heat. Add zucchini, onion, green pepper and garlic; cook for 3 minutes, stirring occasionally. Stir in beans, tomato sauce, chili powder and cumin. Simmer, covered, for 5 minutes, stirring occasionally. Set aside.Advertisement
Heat broiler to high; set rack 6 inches from heat source. Heat a large nonstick skillet over medium-high heat. Add frankfurters and cook, turning frequently, for 3 to 4 minutes or until browned and heated through. Place frankfurters in rolls and place on large broiler pan. Spoon 1/4 cup of the chili over each and sprinkle with 2 tbsp cheddar. Reserve remaining 2 cups chili for another meal.
Broil on high for 1 to 2 minutes or until cheddar is melted. Top with chopped onion and diced cucumber, if desired.