Season the Chicken Thighs: Place the chicken thighs on a cutting board and pat them completely dry with paper towels. Combine the cumin, smoked paprika, garlic powder, onion powder, kosher salt, and black pepper in a small bowl and stir until uniform. Sprinkle the spice mixture evenly over both sides of each thigh, pressing gently with your fingers so the rub adheres to the surface. Dry chicken forms a better sear because surface moisture delays browning in the pan.
Make the Cilantro-Lime Rice: Combine the cooked rice, fresh lime juice, and chopped cilantro in a medium saucepan over low heat. Stir continuously for 2 minutes until the lime juice absorbs into the rice and the mixture is warmed through. Remove the pan from heat, place the lid on top, and set aside to keep warm. The lime juice seasons the rice without adding extra sodium.
Warm the Black Beans: Add the drained and rinsed black beans and 0.5 teaspoon of kosher salt to a small saucepan over medium heat. Cook for 4 minutes, stirring every 60 seconds, until the beans are heated through and a few begin to split at the skin. Remove from heat and cover to keep warm.
Sear the Chicken Thighs: Heat 2 tablespoons of avocado oil in a 12-inch skillet over medium-high heat for 90 seconds until the oil shimmers and a small piece of chicken sizzles immediately on contact. Place the seasoned thighs in the pan in a single layer without overlapping. Cook for 6 minutes without moving them until the underside develops a deep brown, slightly charred crust that lifts cleanly from the pan.
Finish and Rest the Chicken: Flip each thigh using tongs and cook the second side for 5 minutes until the internal temperature reads 74°C / 165°F on an instant-read thermometer inserted into the thickest part. Transfer the cooked thighs to a clean cutting board and rest for 5 minutes. Resting allows the juices to redistribute so the meat stays moist when sliced.
Slice the Chicken: Hold each rested thigh firmly on the cutting board with one hand. Use a sharp chef's knife to slice across the grain into strips approximately 1cm / 0.4in wide. Cutting across the grain shortens the muscle fibers and produces tender, easy-to-chew pieces inside the burrito.
Warm the Tortillas: Place one flour tortilla directly over a gas burner set to medium flame, or in a dry skillet over medium heat, for 20 seconds per side until the tortilla is pliable, lightly toasted, and shows small charred spots. Repeat with the remaining 3 tortillas. A warm, pliable tortilla folds without cracking and seals the burrito securely.
Build Each Burrito: Lay one warmed tortilla flat on the cutting board. Spread 2 tablespoons of sour cream in a horizontal band across the lower third of the tortilla, leaving 5cm / 2in of space on the left and right edges. Layer approximately 75g / 2.6oz of cilantro-lime rice, 75g / 2.6oz of black beans, one quarter of the sliced chicken, 30g / 1oz of shredded cheese, 2 tablespoons of pico de gallo, and 3 to 4 slices of avocado directly over the sour cream. Keeping the filling compact in a tight horizontal band makes rolling easier and prevents tearing.
Fold and Roll the Burrito: Fold the left and right edges of the tortilla inward over the filling by 4cm / 1.5in on each side. Hold the left and right edges in place with your fingers while you lift the bottom edge of the tortilla up and over the filling, tucking it snugly underneath the filling mound. Roll the burrito forward firmly away from you in one continuous motion until fully sealed, with the seam side facing down. Repeat the assembly and rolling process with the remaining 3 tortillas and filling portions.
Toast the Sealed Burrito: Place each sealed burrito seam-side down in the same skillet over medium heat for 2 minutes until the tortilla is golden and holds its shape without unrolling. Toasting the seam side locks the burrito closed and adds a light crispness to the outer tortilla.
