Ceviche de Corvina.

Corvina is the fish that Panama built a market around. The Pacific side of the isthmus, where the Gulf of Panama pushes cold nutrient-rich water up in the dry season, lands it in quantity, and for decades the Mercado de Mariscos on the edge of Casco Viejo has been where the city goes to buy it — whole on ice at the counters downstairs, or already cured and sitting in styrofoam cups at the stalls outside. That cup is the reference version of this dish for most Panamanians: a few dollars, a plastic fork, a sleeve of saltines, eaten leaning on a railing above the boats.

Curing raw fish in citrus is shared across the whole Pacific coast of the Americas, and Panama makes no claim to have invented it. Peru and Ecuador both have older and more elaborate ceviche cultures, and Panamanian cooks are perfectly aware of it. What Panama did was simplify. The dice got smaller, the cure got longer, and the garnish list shrank to onion and herb. Celery came in somewhere along the way as a cheap, permanently available crunch, and it stuck hard enough that a Panamanian ceviche without it reads as incomplete. The other local marker is culantro rather than cilantro — the long serrated leaf that runs through almost every savoury dish in the country, more bitter and more assertive, and used stems and all.

The long cure has a practical origin. Selling ceviche from a market stall in a tropical climate means the acid has to do real work, not decorative work, so the fish is left until it is cooked through to the centre and firm all the way. That is why Panamanian ceviche keeps better than most and why it is one of the few versions that genuinely improves after half an hour rather than deteriorating. Restaurants across the city now serve it in tasting portions with plantain chips, and Afro-Antillean and Chinese-Panamanian stalls sell variations with coconut milk or soy alongside the standard, but the plastic cup and the packet of crackers remain the honest form of the dish.