Ceviche verde mexicano (green ceviche)

Chill all ingredients, bowls, and serving glasses thoroughly before beginning. Warm ceviche presents a food-safety risk and dulls the cure. Everything is ready when the mixing bowl is cold to the touch.

Cut the peeled, deveined shrimp into 1 cm pieces. Consistent size is essential: uneven cuts cure at different rates, leaving some pieces underdone and others rubbery. Place in the chilled bowl.

Pour the fresh lime juice over the shrimp. Add the finely diced tomatillo — its natural acidity supplements the lime, so no additional acid is needed. Stir once to coat. The shrimp must cure for 20–30 minutes: this is where the dish lives or dies. Under 20 minutes the centres remain translucent and raw; beyond 45 minutes the texture turns rubbery and the protein toughens irreversibly. At 20–30 minutes the shrimp pieces are opaque throughout but yield gently to the touch.

When the cure is complete, drain off the excess lime and tomatillo liquid. Add the finely diced cucumber, chopped serrano chile, and cilantro. Season with fine sea salt. Stir to combine. The mixture should smell bright and clean — lime, fresh herb, and seafood with no ammonia note.

Dice the avocado and fold it in immediately before serving. The avocado must not contact the lime cure during the marinating period — it oxidises and develops bitter notes. At service it should appear a clean, pale green with no browning.

Spoon into chilled glasses or cups. Serve at once with tostadas alongside. The finished ceviche should be distinctly cold, light, and bright — not pooled in liquid.