Preheat the oven to 350ºF.

In a large skillet, heat the oil over medium heat. Add the tortillas in batches and lightly fry until crisp. Transfer the tortillas to a plate.

Increase the heat to high and add the bell pepper and corn. Cook, stirring often, until blistered. Transfer the peppers and corn to a second plate.

Add the refried beans to the pan to warm through.

Arrange 4 of the tortillas on a baking sheet in a single layer and spread with the refried beans. Evenly top with half of the pepper and corn mixture, then half of the cheese, then the remaining tortillas.

Spread the salsa over the tops of the pizzas, then top with the remaining pepper and corn mixture, remaining cheese, and tomatoes. Sprinkle with the taco seasoning.

Bake until the cheese is melted, about 5 minutes. Slice the pizzas into quarters and top with the avocado and scallions.