To prepare dressing, combine first 4 ingredients, stirring well with a whisk.
To prepare tacos, place tortillas in a zip-top plastic bag; microwave tortillas at high 40 seconds. Divide Margarita Grouper Fillets and onion evenly over half of each tortilla; drizzle each serving with about 2 teaspoons dressing. Fold tortillas in half. Serve with lime wedges.
(Totals include Margarita Grouper Fillets)