Prepare the mango salsa by combining the diced mango, red bell pepper, red onion, cilantro, jalapeño, and lime juice in a medium bowl. Stir well and set aside to let the flavors meld.
Preheat your grill to medium-high heat (around 400°F). Lightly oil the grill grates to prevent sticking.
Pat the halibut fillets completely dry with a paper towel. Brush both sides of the fillets evenly with olive oil.
Season the fillets on all sides with the sea salt, black pepper, and garlic powder.
Place the seasoned halibut directly onto the hot grill. Close the lid and cook for 4-5 minutes until grill marks appear.
Carefully flip the fillets using a fish spatula. Cook for an additional 3-4 minutes, or until the internal temperature reaches 130°F to 135°F and the flesh is opaque.
Remove the halibut from the grill and let it rest for 2-3 minutes.
Serve the warm grilled fillets topped generously with the fresh mango salsa.