In a small bowl, whisk together honey, lime juice, olive oil, minced garlic, cumin, salt, and pepper. Place chicken breasts in a resealable bag or shallow dish, pour marinade over them, and turn to coat. Refrigerate for at least 15 minutes (or up to 2 hours for more flavor).
In a medium bowl, combine diced mango, red onion, cilantro, jalapeño (if using), lime juice, and salt. Stir gently to mix. Set aside at room temperature to let flavors meld.
Preheat an outdoor grill or indoor grill pan to medium-high heat (about 400°F). Remove chicken from marinade, letting excess drip off. Grill chicken for 5-7 minutes per side, or until internal temperature reaches 165°F and the outside has nice grill marks. Let rest for 5 minutes before slicing.
Divide warm rice among 4 plates. Slice each chicken breast against the grain and place on top of rice. Spoon a generous amount of mango salsa over the chicken. Garnish with fresh cilantro and serve with lime wedges on the side.