Make the mango salsa: In a medium bowl, combine the diced mango, finely diced red onion, chopped jalapeño, lime juice, and fresh coriander. Stir gently until everything is well mixed. The salsa should look vibrant and glossy, with the mango pieces glistening from the lime juice. Set aside to allow the flavours to meld while you prepare the fish.

Prepare the fish seasoning: In a small bowl, mix together the ground cumin, smoked paprika, garlic powder, salt, and black pepper. The aroma that rises from the bowl is warm and slightly smoky—this is your flavour base.

Season the mahi-mahi: Pat the mahi-mahi fillets dry with kitchen paper. This is important because a dry surface helps the seasoning stick and encourages a good sear. Rub the spice mixture evenly over both sides of each fillet. You will see the spices form a thin, fragrant crust on the fish.

Cook the fish: Heat the olive oil in a large frying pan over medium-high heat. When the oil shimmers and you see the first wisp of smoke, carefully place the seasoned fillets in the pan. You should hear a satisfying sizzle on contact. Cook for 3-4 minutes without moving the fish, until the underside is golden brown and releases easily from the pan. The edges will look opaque and slightly crisp.

Flip and finish cooking: Gently flip each fillet using a spatula. Cook for another 2-3 minutes, until the fish is cooked through and flakes easily when tested with a fork. The internal temperature should reach 63°C (145°F). The flesh will have turned from translucent to a firm, snowy white all the way through.

Warm the tortillas: While the fish rests for a minute, warm the tortillas. You can do this directly over a gas flame for about 30 seconds per side, until they have slight char marks and are pliable. Alternatively, wrap them in a clean tea towel and warm them in a dry pan or microwave. They should feel soft and warm to the touch.

Assemble the tacos: Flake the cooked mahi-mahi into large chunks using a fork. Divide the flaked fish among the warm tortillas. Top each taco generously with the mango salsa, a sprinkle of crumbled feta or cotija cheese, and a few slices of avocado if using. Serve immediately, while the fish is still warm and the salsa is cool and refreshing.