Preheat the oven to 400°F, and poke holes in the sweet potatoes with a fork. When the oven is preheated, cook the potates for roughly an hour.
Check the potatoes after an hour - if they're very large, they made need more time. They're done when they pierce easily with a knife.
Meanwhile, cook the chicken: clean excess fat and pat try. Mix the cumin, chili powder, salt and cayenne in a small bowl and then use half of it to coat the chicken. Set the other half aside.
Heat 1 tbsp olive oil in a nonstick pan. When it's nearly smoking, add the chicken thighs and cook on medium high for 4 minutes. Flip to the other side and cook another 4-6 minutes. It's done when the internal temperature reaches 165°F.
Set the chicken aside. Add remaining oil to pan, then saute the onion for 3 minutes, until starting to brown. Add the garlic and cook another minute. Add the corn, black beans, and remaining seasoning. Cook on medium until everything is hot and onions are cooked the way you like them.
To serve, start with an opened sweet potato. Pile up the corn and bean mixture, add a layer of sliced chicken, and then top with sliced avocado!