If using ahi tuna or white fish: Pat fish dry and cut into 1/4-inch cubes. If using shrimp: if raw, poach briefly (2–3 minutes) until just opaque then cool in ice water; if already cooked, slice to bite-size. If using octopus (pulpo): thinly slice cooked octopus into bite-size pieces.

Marinate

Place the cubed protein in a non-reactive bowl. Add fresh lime juice and lemon juice so the protein is mostly immersed. Sprinkle sea salt and black pepper over the top. If you want a slightly less acidic result, stir in 1 tablespoon ice water. Gently toss to coat.

Cure time

For ahi tuna: marinate 6–8 minutes for a lightly 'cooked' exterior but still sashimi-like center. For firm white fish: 10–12 minutes until opaque. For raw shrimp: 12–15 minutes. For cooked shrimp or cooked octopus: 2–3 minutes just to marry flavors (do not over-marinate). Timing is approximate—taste for doneness.

Aromatic & Vegetable Mix

While the protein is marinating, combine the thinly sliced red onion, minced chile, diced tomato, diced cucumber (if using), and chopped cilantro in a bowl. Lightly season with a pinch of salt to draw out moisture and toss.

After the protein reaches the desired cure time, drain off about half of the excess citrus (leave enough to coat). Add the aromatic-vegetable mixture to the marinated protein and gently fold together until evenly distributed.

Finishing & Garnish

Drizzle the extra-virgin olive oil over the ceviche and fold in the diced avocado carefully so it doesn't mash. Adjust seasoning with additional salt, a grind of black pepper, or a splash more lime if needed.

Plate the ceviche chilled or at cool-room temperature. Sprinkle toasted corn kernels or place tortilla chips alongside for crunch. Garnish with microgreens or baby cilantro and a lime wedge.

Serve immediately. If storing, keep refrigerated and consume within 12 hours for best texture—note that prolonged marination will continue to 'cook' the protein and change texture.