In 10-inch nonstick skillet, heat oil over medium-high heat. Cook eggplant, bell pepper and onion in oil 5 to 7 minutes, stirring occasionally, until vegetables are crisp-tender.
Stir in tomatoes and salt; reduce heat to medium. Cover and cook about 5 minutes or until eggplant is tender.
Spread scant 2 tablespoons hummus inside each taco shell. Spoon about 1/2 cup vegetable mixture over hummus in each shell. Serve with yogurt.