Poisson cru — the Tahitian national dish — is fresh tuna sashimi cubed and marinated quickly in lime juice, then dressed with coconut milk, diced cucumber, tomato and onion. It's served everywhere on the island; the best are the simple ones with tuna that came out of the lagoon that morning.
The upstairs of the Marché de Papeete is one of the cheapest reliable places — a half-dozen lunch counters serve poisson cru with rice and a couple of sides for 1,200-1,500 XPF, and the turnover guarantees the fish is fresh. The roulottes on Place Vai'ete also do good versions, but the lunch service at the market is the local favourite. Eat it the moment it lands — the lime cooks the fish further if you wait.