Add thinly sliced red onion to the brine, pressing to submerge. Let sit at room temperature for at least 20 minutes; for best flavor refrigerate 1 hour to overnight. Drain before using.

Citrus Slaw

In a medium bowl whisk together mayonnaise, Greek yogurt, lime juice, honey, apple cider vinegar, salt, and black pepper until smooth.

Add the sliced green and red cabbage, grated carrot, and chopped cilantro to the dressing. Toss to coat evenly. Taste and adjust salt or lime as needed. Refrigerate until ready to serve (can be made 2 hours ahead).

Blackened Mahi Mahi

Pat mahi mahi fillets dry with paper towels. If fillets are large, cut into 8 pieces to match tortillas (about 3–4 oz each).

In a small bowl mix smoked paprika, ground cumin, dried oregano, garlic powder, onion powder, black pepper, kosher salt, and cayenne pepper to make the blackening spice.

Brush both sides of the fish lightly with olive oil, then press the spice mixture onto both sides so fish is evenly coated.

Heat a large cast-iron skillet or heavy sauté pan over medium-high heat until very hot. Add the butter and let it melt and begin to foam.

Carefully place the seasoned fillets in the hot pan. Cook undisturbed 2–3 minutes per side, depending on thickness, until a dark crust forms and the fish is opaque and flakes easily with a fork (internal temp 135–140°F/57–60°C).

Remove fish to a plate, squeeze 1 tablespoon fresh lime juice over the cooked pieces, and let rest 2 minutes. Flake into bite-sized pieces for tacos.

Warm Tortillas & Assemble

Warm the tortillas in a dry skillet over medium heat 20–30 seconds per side or wrap in foil and heat in a 350°F (175°C) oven 8–10 minutes. Keep wrapped to stay warm.

To assemble each taco: place about 2 tablespoons of citrus slaw on a warm tortilla, add a portion of flaked blackened mahi mahi (about 3–4 oz), top with pickled red onion, a couple slices of avocado, and a few cilantro leaves.

Finish with a squeeze of lime and a few drops of hot sauce if desired. Serve immediately.