Ceviche Clásico

Slice the red onion as thinly as humanly possible — ideally 1 mm or less, using a mandoline or a very sharp knife. Place in a bowl of cold, lightly salted water. Soak for 10 minutes — this draws out sulfurous compounds and raw bite while preserving the clean onion flavor and brilliant purple-pink color. Drain, rinse, and drain again. In the same bowl, toss the drained onion slices with a pinch of salt and a small squeeze of lime juice. The salt seasons while beginning to macerate the onion, making each slice supple and bright. Set aside. Properly prepared onion is the texture counterpoint that makes ceviche: it must be crisp enough to have presence, soft enough to not be harsh. The soaking step is non-negotiable for a refined result.

In a chilled glass or ceramic bowl, combine the sea bass cubes with the salt and toss gently to season. Pour the lime juice over the fish — the juice must completely cover every piece. Add the ají amarillo paste, grated ginger, grated garlic, and ají limo. Toss very gently with a spoon, turning the fish once or twice without breaking the cubes. Do not mix vigorously — you are not making a salad. Place the bowl directly on ice or in the freezer for exactly 2–3 minutes. In Lima, ceviche marinates for only 2–3 minutes — the fish is barely touched by the acid, remaining almost raw at the center while the outermost layer turns opaque. This is the Limeño style: vital and immediate, consumed the moment it's ready. The remaining lime juice, now loaded with fish essence, ají heat, ginger, and brine, is the leche de tigre — tiger's milk. It is one of the most flavourful liquids in all of cooking.

Working quickly — the moment you stop moving, the fish continues to cure — add the macerated onion slices directly to the ceviche bowl. Add the cilantro leaves whole or gently torn, never chopped (chopped cilantro bruises and turns dark). Toss everything together with two spoons, using three or four gentle, lifting motions. Taste the leche de tigre and adjust seasoning: it should be explosively sour-salty-hot, but the heat should build rather than ambush. If it's too sour, a pinch of sugar helps; if too flat, more salt. Divide immediately among two chilled bowls. Fan slices of boiled sweet potato along one side — the camote's gentle sweetness is the traditional counterweight to the acidic fish and the textural rest your palate needs. Scatter cancha or chifles over the top for crunch. Serve within 30 seconds of plating. Ceviche does not wait. Invite your guests to drink the leche de tigre from the bowl.