01 - In a large mixing bowl, whisk together the honey, lime juice, olive oil, minced garlic, ground cumin, chili powder, kosher salt, black pepper, and lime zest until well blended and smooth.
02 - Place the chicken breasts in a large resealable plastic bag or a shallow baking dish. Pour the marinade over the chicken, seal tightly, and turn to coat each piece evenly. Marinate at room temperature for 20 minutes, or refrigerate for up to 2 hours for more pronounced flavor.
03 - While the chicken marinates, combine the diced mangoes, red bell pepper, red onion, minced jalapeño (if using), chopped cilantro, lime juice, and salt in a medium bowl. Toss gently to incorporate all ingredients. Taste and adjust the salt and lime juice as needed. Cover and refrigerate until ready to serve.
04 - Preheat an outdoor grill or grill pan to medium-high heat, approximately 400°F. Lightly brush the grill grates with olive oil to prevent sticking.
05 - Remove the chicken from the marinade, allowing any excess to drip off. Discard the remaining marinade. Place the chicken on the hot grill and cook for 6 to 7 minutes per side, or until the internal temperature reaches 165°F and the exterior shows defined char marks. Transfer to a cutting board and let rest for 5 minutes before slicing.
06 - Slice the rested chicken breasts against the grain and arrange on serving plates. Spoon a generous portion of the chilled mango salsa over each portion. Serve immediately.