Shrimp Aguachile

Using a sharp knife, butterfly each shrimp by cutting along the back (where the vein ran) almost all the way through, then pressing it open flat. This doubles the surface area exposed to the cure and allows the lime juice to penetrate more quickly and evenly. Arrange the butterflied shrimp in a single layer in a cold, shallow dish. Refrigerate while you prepare the aguachile.

Blend half the cucumber (peeled and roughly chopped), all the lime juice, serranos, and salt together in a blender for 60 seconds until completely smooth and vivid green. Strain through a fine sieve, pressing the solids to extract maximum liquid. Discard solids. The aguachile should be intensely green, bracingly acidic, and fiercely hot. Taste it — it should feel aggressive. Adjust heat by adding or removing serrano seeds.

Pour the aguachile verde over the shrimp, ensuring every piece is fully submerged. The shrimp should cure for exactly 7-10 minutes — the lime juice denatures the proteins in the same way heat would, turning the flesh from translucent grey to opaque white-pink. Do not over-cure. At 10 minutes, the shrimp should be pink-white on the outside but still slightly translucent at the very center — this is the perfect texture. Longer curing produces rubbery, overcooked-tasting shrimp.

Arrange the cured shrimp on a cold, flat plate. Drape thinly sliced onion half-moons over the shrimp. Layer cucumber slices around the plate. Spoon 2-3 tablespoons of the aguachile verde over everything. Scatter cilantro leaves. Serve immediately with tostadas or thick tortilla chips on the side. The dish should be cold, bright, and served instantly — aguachile waits for no one.