Preheat oven to 400 degrees F. Spray both sides of the flour tortillas with cooking spray. Sprinkle a little bit of salt on each side of the tortilla. Using a fork, poke little holes all over the tortillas. This will prevent them from puffing up in the oven. Place on a large baking sheet and bake for 4-5 minutes, then turn tortillas over, and bake for 3-5 minutes longer until the tortillas are crisp and light brown. Set aside.

Preheat grill to medium-high heat. Brush the zucchini and corn lightly with olive oil. Season with salt and black pepper, to taste. Place zucchini and sweet corn on hot grill and cook until charred and just beginning to soften, about 7-10 minutes. Remove from grill and let cool to room temperature. Chop the zucchini into pieces. With a sharp knife, carefully remove the corn kernels from the grilled sweet corn ears.

Top each crisp tortilla with zucchini, corn, green onion, cilantro, and avocado. Squeeze fresh lime juice over the top and garnish with cotija cheese. Serve immediately.