In a large skillet, heat 1 1/2 tablespoons of the olive oil over medium high. While the oil heats, combine the chili powder, cumin, kosher salt, and cayenne pepper in a small bowl. Once the oil is hot and shiny, add the zucchini rounds in a single layer, then sprinkle with half the spice mixture. Let cook until the first side is golden, about 4 minutes, then flip, sprinkle with the remaining spice mixture, and cook on the other side until it is golden as well, 3-4 additional minutes. Remove to a plate and cover to keep warm.

Reduce the skillet heat to medium low. Add the onion and corn and let cook until beginning to soften, about 5 minutes. Add the garlic and beans, then cook until the garlic is fragrant and the beans are heated through, about 2-3 minutes.

If desired, toast the tortillas over a gas burner or cover with a lightly damp paper or kitchen towel and warm in the microwave. Fill tortillas with the bean mixture and reserved zucchini slices, then add any desired toppings. Enjoy immediately.