Step 1Place the onions in a medium, heavy-bottomed saucepan and pour in enough water to cover. Bring to a boil, and remove from the heat. Strain and set aside the onions.
Step 2Combine the vinegar, black pepper, cumin, oregano, garlic, sugar, salt and beet in the saucepan. Bring to a boil, reduce to a simmer and cook 7 minutes. Add the blanched onions and gently simmer an additional 7 minutes. Transfer the mixture to a container, cover and refrigerate at least a day before serving. This makes about 2 1/2 cups pickled onions, more than is needed for the remainder of the recipe. Pickled onions will keep in the refrigerator up to a month.
Step 1In a large glass or nonreactive bowl, combine fish and the lime juice to cover. Marinate for 20 minutes, tossing occasionally. Drain the fish, reserving a quarter-cup of lime juice.
Step 2Combine the fish with the onion, chile, jalapeno, ginger, oil, cilantro and chile paste. Stir in the lime juice. Chill thoroughly. Drain the ceviche and season to taste with salt. Serve each portion in a chilled martini glass, garnished with plantain chips or tortilla chips, pickled red onions and slices of avocado.