In a blender, combine the avocado with the roasted poblano and jalapeno peppers, 1/4 cup of the olive oil, 1/4 cup of the chopped onion, 1/4 cup of the cilantro leaves, the lime juice, 1/4 teaspoon of the kosher salt and the water. Puree until smooth and set aside as you prepare the rest of the dish.
Preheat a cast iron grill pan over medium heat. Season the amberjack with the remaining teaspoon of kosher salt and the white pepper. Rub both sides of the fish with the remaining 3 tablespoons of olive oil and place in the grill pan. Sear until just cooked through, about 4 minutes on each side. Remove from the pan and set aside.
To assemble the tacos, divide the fish (in flakes or small chunks) evenly among the tortillas. Place 1 tablespoon of the chopped onion and 1 tablespoon of the cilantro leaves over the fish. Place a half tomato slice over the onions and cilantro and spread some of the Roasted Chile and Avocado Salsa over the tomato and fish. Squeeze some lime juice over the tacos, fold over and eat. Repeat with the remaining tortillas, fish and other ingredients.