Port Louis has the best and most varied eating on the island, reflecting the full range of Mauritian culinary influences — Indian, Chinese, Creole, and French.
The central market is the place to start. The food vendors on the upper floor sell dholl puri, roti, mine frite, and boulettes for a few rupees each — better than anything at tourist prices. Go for lunch on a weekday when it's busiest.
Chinatown, a few streets north of the market, has a cluster of Chinese restaurants where you can eat well for under Rs 500 per person. The cooking is honest and filling; don't expect anything glamorous.
La Flore Mauricienne, across from the parliament building, has been there since 1848 and calls itself the oldest restaurant in the city. It's a reliable lunchtime spot with Mauritian and French dishes at reasonable prices.
The Caudan Waterfront has a large concentration of restaurants and bars with good views of the harbour. Food and drink prices here are significantly higher than elsewhere in the city — budget double what you'd pay in the market. The Keg and Marlin is a long-running pub in the waterfront complex, popular with locals and expats.
Le Safran in the city centre does good Indian cooking. For fresh fish, explore the streets around the fishing port early in the morning where vendors sell the night's catch.