Add Onion (1/2) to a bowl of hot water for 30 seconds, then drain. Add to a bowl of cold water for 30 seconds, then drain. This removes the spicy bite of the raw onion.
Finely dice seeded Jalapeño Pepper (2). Discard the seeds and pit.
Finely mince the Garlic (1 clove).
Dice the Tomato (3) and roughly chop the Fresh Cilantro (1/4 cup).
In a bowl, add the tomatoes, raw onion, chopped cilantro, garlic, Apple Cider Vinegar (2 tablespoon), Lime Juice (2 tablespoon), Olive Oil (1 tablespoon), Agave Syrup (1 teaspoon) and Salt and Pepper (to taste). Toss and marinate in the fridge for 30 mins.
In a shallow bowl, whisk Canola Oil (3 tablespoon), Ground Cumin (1 teaspoon), Chili Powder (1 teaspoon), Lime Juice (2 tablespoon) and Kosher Salt (1/2 teaspoon).
Slice your Mahi-Mahi Fillet (1 pound) into manageable pieces. Toss and marinate for at most 20 minutes. The acid in the lime will cook the fish so don't marinate any longer.
Toast your White Corn Tortilla (12) on both sides directly on the gas flame and then wrap them in tin foil to keep warm.
Dice the Avocado (to taste).
Thinly slice the Iceberg Lettuce (1/4).
Place a large pan over medium high heat. Cook the marinated fish without moving until the underside of the fish is browned, and the sides are white and opaque, about 3 minutes.
Flip and sear on the other side until white and opaque, about 2 minutes more, or until cooked through. Transfer the fish to a plate. It’s okay if it falls apart.
Drain your salsa. You can save the juice and add it to some yellow rice to give it a fresh taste.
Assemble your taco with some of the cooked fish, and top it with lettuce, fresh salsa, Sour Cream (to taste), avocado, and any other optional garnishes.