Preheat your oven to 425 degrees Fahrenheit and prepare a baking sheet by lining it with parchment paper for easy cleanup. Spread the cubed sweet potatoes evenly across the sheet and drizzle them with one tablespoon of olive oil. Use your hands or a spatula to toss the cubes until they're well coated. Roast the sweet potatoes in the oven for 20 to 25 minutes, or until they become fork-tender and lightly browned, making sure to toss them once about halfway through the cooking time for even roasting.

While the sweet potatoes are in the oven, heat one tablespoon of olive oil in a large skillet over medium-high heat. Add the sliced red onion and frozen corn to the pan, stirring frequently for about two minutes until they begin to soften and develop flavor. Next, add the chopped zucchini and continue cooking, stirring often, for another 3 to 4 minutes, until the zucchini starts to turn tender but still has a slight bite.

Lower the heat to medium and stir in the minced garlic, drained black beans, chili powder, cumin, salt, and black pepper. Cook the mixture for 1 to 2 more minutes, stirring constantly to warm the beans through and allow the spices to bloom. Once the sweet potatoes are done roasting, gently fold them into the skillet with the rest of the ingredients and stir to combine. Remove the pan from the heat and set it aside.

To warm the tortillas, place them between two paper towels and microwave for about 20 to 30 seconds until soft and pliable. Alternatively, you can warm them in a dry skillet over medium heat for a few seconds on each side.

Fill each tortilla with a generous spoonful of the black bean and vegetable mixture. Top with sliced avocado and shredded cheese, then serve immediately while everything is warm and flavorful.