Preheat oven to 350F. Heat oil in a saucepan. Add sausage, onion, garlic, cumin and chili powder; fry gently 5 minutes, stirring to break up sausage. Add tomato, tomato paste, bell pepper and kidney beans. Stir well and cook gently 15 minutes, stirring frequently to prevent mixture sticking. Season with salt. Meanwhile, heat taco shells following package instructions. Fill hot taco shells with sausage mixture. Top each taco with sour cream and sprinkle with paprika. Serve with lettuce leaves and radish roses. VARIATION: Substitute lean ground beef for sausage, if desired.