In a small bowl, mix together 1 teaspoon kosher salt, 2 teaspoons smoked paprika, 2 teaspoons garlic powder, 1 teaspoon dried thyme leaves, ½ teaspoon onion powder, and ½ teaspoon cayenne pepper.
Pat the fish dry with paper towels. Sprinkle the cajun seasoning blend evenly over both sides of the fillets, rubbing the mixture into the fish with your hands.
Place a large saute pan over medium-high heat and add 2 tablespoons unsalted butter and 1 tablespoon extra virgin olive oil. Once the butter is melted and the oil is hot, add the seasoned fish. Work in batches with half the oil and butter if needed.
Cook, undisturbed, for 3 minutes, or until golden brown. Gently flip the fish over and continue to cook, undisturbed for an additional 2-4 minutes, or until the fish is browned on the opposite side, and opaque.
Remove the fish from the skillet, and squeeze a wedge of fresh lemon or lime over each fillet. Serve immediately.
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Notes
Fish: Use 4 to 6-ounce, ½-inch thick white, firm fish fillets for this recipe. Halibut, seabass, grouper, or snapper can be substituted for the mahi-mahi.Seasonings: Feel free to use 2 tablespoons of your favorite cajun seasoning in place of the homemade blend. Heat Level: Either decrease or increase the cayenne pepper according to your spice tolerance. Note on Working in Batches: If your skillet only fits 2 fillets, use half the amount of oil and butter for each batch, wiping the skillet dry between batches.Storage: Fish is best served immediately after preparation. However, if you happen to have leftover mahi-mahi, store it in an airtight container in the refrigerator for up to 48 hours. Reheat in a dry skillet over medium heat for a couple of minutes per side, or until warmed through, and squeeze fresh lemon juice over the fish immediately before serving.