For the salsa:
1 small green bell pepper
4 medium tomatillos, husked and rinsed
1/2 cup loosely packed fresh cilantro leaves
1/2 large ripe avocado
1 medium garlic clove
2 teaspoons fresh lime juice
1/4 teaspoon kosher salt
1/4 teaspoon freshly ground black pepper
1 Romaine lettuce heart
4 skinless red snapper fillets, about 6 ounces each
1 teaspoon ancho chile powder
1/2 teaspoon kosher salt
8 to 10 flour tortillas (10 inches)
1. To make the salsa: Grill the bell pepper over Direct High heat until the skin is black and blistered, 10 to 12 minutes, turning every 3 to 5 minutes. Remove from the grill and place in a paper bag; close tightly. Let stand 10 to 15 minutes to steam off the skins. Remove the pepper from the bag and peel away the charred skin. Cut off the top and remove the seeds. Set aside. Grill the tomatillos over Direct High heat until they well marked and beginning to collapse, 4 to 6 minutes, turning occasionally. Put the tomatillos and the bell pepper in the bowl of a food processor and process for a few seconds. Add the remaining salsa ingredients, including Tabasco to taste. Process until well combined but still a bit chunky. Set aside in a bowl.
2. Clean, core, and cut the lettuce into thin, crosswise slices and put into a bowl. Lightly brush or spray both sides of the fish fillets with vegetable oil and season with the ancho chile powder and salt. Grill over Direct High heat until the fish begins to flake, 3 to 4 minutes, turning once halfway through grilling time. Remove from the grill. Separate into large flakes with two forks and put into a bowl. Heat the tortillas over Direct High heat for about 30 seconds, without turning. Wrap in a kitchen towel to keep warm. Pile the lettuce and fish on the warm tortillas and top with the salsa.