Preheat your oven to 400°F, positioning the rack in the center.

Prepare the Lemon Garlic Mixture ahead of time by blending all the ingredients in a small pan until they are well combined. Set this mixture aside for later use.

Ensure the mahi mahi fillets are thoroughly dried using paper towels to remove any excess moisture. Season both sides of the fish with a sprinkling of kosher salt and freshly ground black pepper. Set the seasoned fillets aside.

In a large, oven-safe skillet, heat the olive oil over high heat until it is sizzling hot. Add the mahi mahi fillets to the pan, letting them cook undisturbed for about 3 minutes until they are browned on one side.

Carefully flip the fillets over, turn off the stove, and immediately transfer the pan to the preheated oven.

Roast the fish at 400°F for approximately 5 minutes, or until the tops are golden and the centers are just cooked through. Avoid overcooking. About a minute before the fish is finished, reheat the prepared lemon-garlic mixture over medium-high heat, stirring constantly until it is melted and bubbly.

Once melted, remove from heat and pour the mixture over the cooked fish fillets, ensuring to include any juices from the pan. Garnish with extra lemon slices and serve immediately.