Preparation

• Heat a large nonstick skillet over medium-high heat. Rub the chicken all over with the oil, and season well with salt and pepper. Cook the chicken for 1 minute, flip, cover, reduce the heat to low, and cook for 8 minutes. Remove from the heat and let sit for another 8 minutes.
• Meanwhile, in a medium bowl, coarsely mash the avocado. Stir in the tomato, onion, cilantro, jalapeño, lime juice, garlic, and 1/2 tsp. salt. Season to taste with additional salt and lime juice.
• Using tongs, transfer the chicken to a cutting board to rest briefly. In a bowl, stir 1 Tbs. of the pan juice into the sour cream. Spread some sour cream on the bun bottoms. Top each with half of the chicken, half of the guacamole, and the top of the bun. Serve.