Black Bean Tostadas

0 Preheat broiler to 350 degrees. Spray a baking sheet with cooking spray.
1 Warm up the corn tortillas in a microwave, wrapped in a paper towel (about 30 seconds). Place the corn tortillas on the baking sheet, spray tops of tortillas lightly with cooking spray.
2 Put the tortillas under the broiler, bake until golden brown and crispy.
3 Heat a pan over medium high heat. Add olive oil, onions, garlic, and tomatoes to the pan. Let cook for 10 minutes.
4 Add zucchini, cook until tender - 10 to 12 minutes. Add corn, beans, oregano, pepper, salt to taste (if needed). Cook 3-5 minutes.
5 Split filling among the tostada shells, top with 2-4 tsp salsa and no more than 1-2 Tbsp of cheese.