Preheat the grill to medium-high heat (around 400°F).
Cut the mangoes in half lengthwise, leaving the skin on. Remove the pit and score the flesh of each mango half in a criss-cross pattern, being careful not to cut through the skin.
In a small bowl, whisk together the avocado oil, lime juice, chili powder, cumin, salt, and pepper to create a marinade.
Brush the marinade generously over the scored flesh of each mango half, making sure it seeps into the cuts.
Place the mango halves on the preheated grill, flesh side down. Grill for 3-4 minutes, or until char marks appear.
Using tongs, carefully flip the mango halves over so the skin side is down. Grill for an additional 3-4 minutes, or until the mangoes are heated through and the flesh is slightly softened.
Remove the grilled mangoes from the heat and let them cool for a few minutes.
Sprinkle the lime zest over the grilled mangoes and garnish with chopped fresh cilantro.