Fresh ceviche is the thing to eat in Potrero. The local version — corvina or tilapia marinated in lime juice with onion, coriander, and a little chilli — is served at nearly every soda and beachside stand, and the quality is reliably high when the fish is as fresh as it should be this close to the water. Accompanied by patacones (twice-fried green plantain) and a cold beer, it is a near-perfect lunch after a morning on the beach.
Beyond ceviche, the catch of the day is worth asking about anywhere you eat. Mahi-mahi, red snapper, and sea bass appear regularly, grilled simply or cooked in garlic butter. Some of the more ambitious kitchens do whole fish in the Guanacaste style with rice cooked in coconut milk, a preparation that suits the surroundings well. Lobster and prawns are available at the more tourist-oriented restaurants; quality and price vary accordingly.
The fishing boats return to the beach in the mornings, and the best lunch spots buy directly from the fishermen — making an early start a reliable indicator of a good kitchen.