Ceviche

Method

1. slice10 min
   fish very cold, knife sharp
   fish into even 2 cm cubes against the grain — acid penetrates from the cut surface inward at a fixed rate, so uniform cubes finish together and ragged ones give you chalky corners next to raw centers. Use fish that was frozen at some point: lime does not reliably kill parasites, it only denatures protein
2. prep5 min
   cold running water
   red onion sliced thin, then rinsed and held in ice water — this strips the sulfur compounds that would otherwise leach into the lime and turn the whole bowl harsh and oniony within minutes
3. season3 min
   chilled bowl
   fish + salt, tossed and left to stand — salt draws a little surface moisture and pre-firms the myosin, which is why salted fish takes the acid evenly instead of blotching
4. mix2 min
   cold
   lime juice + garlic + aji amarillo + black pepper + ice cubes, stirred until the ice barely melts = leche de tigre. Cold slows denaturation to a pace you can control; room-temperature lime overcooks the outside before the inside registers anything
5. marinate5 min
   refrigerator or over ice, fish submerged
   fish + leche de tigre, stirred once. The lime drops the pH below about 4.5, which unfolds the muscle proteins and lets them cross-link into an opaque, firm network — the same end state heat produces, reached by a different road. Pull it when the outer 3 mm is white and the center is still glassy; past ten minutes the network keeps tightening and squeezes out water, and the fish goes from silky to cotton
6. fold2 min
   off the acid
   + drained onion + cilantro, folded gently so the cubes stay whole
7. top3 min
   serve immediately
   ceviche into chilled bowls with the leche de tigre spooned over + sweet potato + corn to blunt the acid + chips. It does not hold: the marinade keeps working in the bowl, so anything left twenty minutes later is a different, tougher dish