One of the many joys of Peruvian cuisine is the beautiful way in which it has melded with the foods of immigrants. Nikkei cooking, for example, is Japanese-Peruvian food, the result of a 19-century influx of Japanese migrants to Peru. Peruvian food has influenced the way Japanese food is cooked there, and Japanese food has changed how Peruvians cook. The results are damn delicious.
One fun example is tiradito, which combines elements of ceviche and sashimi in a single dish. Ceviche typically involves "cooking" raw fish in an acidic marinade. One doesn't make ceviche and serve it right away; it's better to wait about 15 minutes until the fish has turned more opaque, and the exterior of each small piece has taken on a partially cooked consistency.
Compare that to Japanese sashimi. While some species like mackerel are cured or seared, many are served completely raw—no heat, no acid, no lengthy salt-curing process. And unlike ceviche's smaller chunks of fish, sashimi is often cut into larger rectangular slices. When served, it's adorned minimally, with soy sauce, wasabi, and pickled ginger on the side.
Tiradito marries the two traditions. Like sashimi, the fish is cut into large slices and spends no time curing before being served. But like ceviche, it's served with a tart, spicy citrus-chili marinade known as leche de tigre (tiger's milk . . . you know, because it's got enough attitude to make you go RAWR).
Some tiradito recipes call for infusing the leche de tigre with pieces of fish and then straining them out and discarding them. This brings it closer to the sauce that comes with a ceviche, in which fish juices have mingled with the marinade. I did not do this for my tiradito recipe, though, since it requires sacrificing some of your (likely pricey) fish to the marinade for what amounts to a nice, but nonessential, step. If you want to do this, though, you can; just soak some fish pieces in the lime juice for 15 or 20 minutes before straining them out and continuing with the recipe (you can, of course, eat those fish pieces in the kitchen, so that they're not totally wasted). If you're working with a whole fish and filleting it yourself, this infusion step becomes much easier since you'll definitely have scraps.
Tiradito sauces come in many flavors, but the most classic features lime juice and a purée made from Peruvian ají amarillo peppers, which have an incredible floral aroma and a decently spicy kick. It varies from pepper to pepper, but it tends to be hotter than your average jalapeño but not nearly as hot as a habanero.
There are a couple ways to get ají amarillo paste in locales where the fresh peppers aren't available. Easiest is to buy a jar of the purée at a market that sells Peruvian ingredients. Better is to make it yourself from frozen whole ají amarillo peppers. The from-frozen stuff has a more complex flavor that captures more of the pepper's natural floral and fruity notes; the jarred option is good, but some of ají amarillo's charms are snuffed out in the canning process. Making your own with frozen peppers is as easy as boiling the peppers for 10 minutes, removing their stems and seeds (and, if you want to be more finicky about it, their skins, too), and then liquifying the flesh in a blender with just enough water to get it moving.
Beyond that, the leche de tigre for tiradito goes like this: Blend fresh lime juice with garlic and some fresh ginger, mix in enough of the ají amarillo paste to give the sauce a punch of chili heat and enough viscosity that it doesn't just flow like water on the plate. Some freshly minced cilantro can go in at the end.
In Peru, the fish is typically white-fleshed, something along the lines of corvina or fluke. Pictured here, though, are salmon and yellowtail (hamachi in Japanese), which are common substitutes, at least here in North America. The important thing is to get fish that you can serve as sashimi; your selection will depend heavily on where you live.
On the side, you might add some choclo (a type of large, white Peruvian corn) or some thick rounds of cooked sweet potato, both of which are traditional tiradito accompaniments. Neither is necessary, though: Tiradito is, at its heart, a dish open to interpretation. It was born of cultures colliding and being flexible enough to embrace each other. Setting its presentation in stone cuts against that spirit.