Begin by heating the avocado oil or olive oil in a large skillet over medium heat. Once hot, add the chopped sweet potatoes. Season with salt, pepper, and optional chili powder. Cook for about 10-12 minutes, or until the sweet potatoes are tender and lightly browned, stirring occasionally.
Add the baby spinach (or your choice of greens) to the skillet with the sweet potatoes. Sauté for an additional 2-3 minutes until the greens are wilted and vibrant.
In a mixing bowl, beat the eggs and season with salt and black pepper. Pour the beaten eggs into the skillet with the sweet potato and spinach mixture. Stir gently, cooking until the eggs are just set, about 3-4 minutes.
In a separate small saucepan, warm the black beans over low heat until heated through. Stir occasionally to prevent sticking.
Warm the corn tortillas in a dry skillet or microwave until pliable. To assemble, layer a generous scoop of the sweet potato and egg mixture onto each tortilla, followed by a spoonful of warm black beans. Top with slices of avocado and grated cheese if desired.
Finish off your tacos with salsa or hot sauce, and a dollop of sour cream or Greek yogurt for a creamy contrast.