Nobu Matsuhisa, it is well known, was the first famous sushi crossover artist, marrying classical Japanese techniques with the pungent flavors he had learned to love as a young sushi chef in Peru. On the one hand, he inflected traditional sushi with heat and exotic spice; on the other, he brought a new, sophisticated gloss to such Peruvian dishes as tiradito, ceviche and mussels a la criolla.

Raw oysters heaped with spicy salsa, commonplace in Lima, became something miraculous and new within the context of a California sushi bar. Tiradito, a Peruvian dish of briefly marinated, thin-sliced fish that was already influenced by Peru’s nikkei — Japanese-immigrant — cooks, was new and brilliant when prepared with top-quality fish, almost a revelation, even when prepared with hot chiles that didn’t happen to be the citrus-tart Peruvian rocoto. Peruvian chefs have always seasoned raw seafood with olive oil and garlic, but it was Matsuhisa’s notion to warm the oil before he drizzled it over the fish and serve it as “new-style sashimi” that may have been the single most imitated dish of the 1990s. Japanese-French, Japanese-Italian and Japanese-Korean restaurants all have their fans, but it is clear that Japanese-Peruvian fusion is the blended cuisine with legs.

Japanese-Peruvian cooking, though, barely exists beyond Matsuhisa, at least in the United States, and although I have collected plenty of recipes for tiradito and friends insist that I missed the appropriate places in Lima, I don’t think I have ever tasted tiradito outside one of his restaurants. So when I drove by the new Japanese-Peruvian Kotosh at Kamiyama, recently carved out of the well-regarded South Bay sushi bar Kamiyama, it seemed like a major discovery, a chance to taste tiradito, pulpo al olivo and chorosa la criolla in their original, “authentic,” unmediated form.

Kamiyama, it must be said, is pretty much a traditional sushi restaurant, with the expected glass-fronted counter, chefs dressed in crisp whites and a list of Japanese sakes and beers. When you sit at the sushi bar, there are hot towels and cups of green tea, fresh yellowtail and seared albacore, salmon-skin hand rolls and bowls of miso soup. The customers at the sushi bar speak mostly Japanese. You could have an entire sushi meal without noticing anything Peruvian about the place at all.

Even before its transformation, Kamiyama was probably best known for its zany rolls, things like “waterpillar” rolls with eel, avocado and cucumber; “krunch” rolls with fried shrimp and eel sauce; and the Hawaiian-style marinated tuna called poke wrapped in soy paper with chile oil and rock salt.

The chefs are especially proud of what they called “SLUR” — the Salmon Lovers’ Ultimate Roll — which is something like a California roll wrapped in Norwegian salmon. Chef Gary Kamiyama developed his initial following when he was the sushi chef at the Gladstone’s on Universal City Walk, undoubtedly a fine place to eat fish but probably lacking the Edo-style rigor of Mori or Urasawa. If you take the trouble to count the produce behind the counter, I suspect you will find as many squeeze bottles of brightly colored sauces as you will different species of fish.

There is an entire menu of Peruvian specialties, and on busy weekend evenings, they seem to appear on two tables out of three: marinated beef or chicken stir-fried with noodles or French fries; vivid-yellow plates of potatoes a la Huancaina in their thick sauce of hard-boiled egg and cheese; a really good milk-based shrimp chowder, sharp with chile and the flavor of sauteed shells, plumped out with chunks of potato. The kitchen does a good version of chicharron de pescado, crunchy slabs of fried fish glazed with a clear, cornstarch-thickened sauce that tastes like pure, browned garlic.

But the best dishes in the restaurant, the best Peruvian dishes anyway, tend to be the ones that pass through the sushi bar — the pulpo al olivo, sliced octopus slicked with a purple emulsion of Peruvian olives and mayonnaise; the cold mussels topped with a fragrant chop of onions, tomatoes and chiles; the ultrafresh ceviche served with the traditional sweet potato, toasted corn kernels and lime. The tuna tiradito is bland, but the tiraditode lenguado, made with halibut sliced carpaccio-thin, marinated in a sauce of fresh lime juice and pureed peppers, and sprinkled with a confetti of minced hot chile, is magnificent — not Matsuhisa, perhaps, but you can see it from here.?

Kotosh at Kamiyama, 2408 Lomita Blvd., Lomita, (310) 257-1363, Mon.–Thurs., 11 a.m.–2:30 p.m. & 4:30–9 p.m.; Fri., 11 a.m.–2:30 p.m. & 4:30–10 p.m.; Sat., 11 a.m.–10 p.m. AE, MC, V. Beer and wine. Takeout. Lot parking. Party platters and catering. Dinner for two, $16–$36, more with sushi. Recommended dishes: tiradito de lenguado, pulpo al olivo, chupo de camarones.

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