In a bowl, whisk together olive oil, lime juice, cumin, chili powder, garlic powder, salt, and pepper. Place chicken breasts in a shallow dish or zip-top bag and pour marinade over. Turn to coat and let sit at room temperature for 15 minutes while you prepare rice.

In a medium saucepan, bring water and salt to a boil. Stir in rice, reduce heat to low, cover, and simmer for 15 minutes. Remove from heat and let stand covered for 5 minutes. Fluff with a fork, then stir in lime juice, chopped cilantro, and olive oil.

Heat a large skillet over medium-high heat. Add a drizzle of oil. Remove chicken from marinade, letting excess drip off. Cook for 6-7 minutes per side, until golden brown and internal temperature reaches 165°F (74°C). Transfer to a cutting board, rest for 5 minutes, then slice into thin strips.

In the same skillet, add black beans and cook for 2-3 minutes over medium heat until warmed through. Meanwhile, heat tortillas one at a time in a dry skillet or microwave for 20 seconds to make them pliable.

Lay a warm tortilla on a clean surface. Spoon about 1/4 of the rice in the center, leaving a border. Top with black beans, sliced chicken, salsa, cheese, sour cream, and a few avocado slices. Drizzle with extra lime juice and sprinkle fresh cilantro.

Fold the bottom edge up over the filling, then fold in both sides. Roll tightly away from you, tucking the edges as you go. Wrap each burrito in parchment paper or foil to hold its shape.

Slice each burrito in half diagonally and serve immediately with extra salsa, sour cream, or lime wedges on the side.