1. 1. Prepare the Chicken Marinade: In a medium bowl, whisk together 2 tablespoons of olive oil, 2 tablespoons of fresh lime juice, 1 tablespoon of fresh orange juice, chili powder, cumin, 1/2 teaspoon salt, and 1/4 teaspoon black pepper. Add the chicken breasts or thighs to the bowl, ensuring they are fully coated. Let the chicken marinate at room temperature for at least 15 minutes while you prepare the salsa, or refrigerate for up to 30 minutes for deeper flavor.

2. 2. Make the Avocado Salsa: While the chicken marinates, prepare the salsa. In a separate medium bowl, gently combine the diced avocados, finely chopped red onion, chopped fresh cilantro, and minced jalapeño (if using). Drizzle with 1 tablespoon of extra virgin olive oil and 1 tablespoon of fresh lime juice. Season with salt and pepper to taste. Toss gently to combine, being careful not to mash the avocado too much. Set aside.

3. 3. Preheat Your Grill or Skillet: Heat an outdoor grill to medium-high heat, or a large grill pan or cast-iron skillet over medium-high heat on your stovetop. Lightly brush the grill grates or pan with the remaining 2 tablespoons of olive oil to prevent sticking.

4. 4. Grill the Chicken: Remove the chicken from the marinade, letting any excess drip off. Place the chicken on the preheated grill or skillet. Cook for 5-7 minutes per side, or until the internal temperature reaches 165 F (74 C) and the chicken is no longer pink in the center. The chicken should have nice grill marks and be juicy.

5. 5. Rest the Chicken: Once cooked, transfer the chicken to a cutting board. Cover loosely with foil and let it rest for 5 minutes. This allows the juices to redistribute, resulting in more tender and flavorful chicken.

6. 6. Slice and Serve: Slice the rested chicken against the grain into desired pieces. Arrange the sliced chicken on plates and generously top with the fresh avocado salsa. Serve immediately.