In a large bowl, combine fish and enough lime juice to cover. Allow to marinate for 20 minutes.
Drain fish, reserving 1/4 cup of lime juice. Combine fish with remaining ingredients and reserved lime juice to taste and stir gently to combine. Chill thoroughly.
Serve in a chilled martini glass, garnished with plantain chips or tortilla chips, Pickled Red Onions, and slices of avocado.
Pickled red onions
Place the onions in a medium saucepan and pour in enough water to cover. Bring to a boil, and remove from the heat. Strain and set the onions aside.
Combine all the remaining ingredients in the saucepan. Bring to a boil, reduce to a simmer, and cook 10 minutes. Add the blanched onions and simmer an additional 10 minutes. Transfer the mixture to a container, cover, and refrigerate at least a day before serving. Pickled onions will keep in the refrigerator up to a month.
Mary Sue Milliken and Susan Feniger are co-chef/owners of the popular, critically acclaimed Border Grill restaurants, serving modern Mexican food in Las Vegas at Mandalay Bay Resort & Casino, as well as in Downtown Los Angeles and Santa Monica, California. They are preeminent ambassadors of authentic Mexican cuisine, setting the standard for gourmet Mexican fare for over two decades and authoring five cookbooks, including Cooking with Too Hot Tamales, Mesa Mexicana, and City Cuisine.