Walloon cooking is hearty: stewed game, river fish, braised meat, big plates of fries, and beer in everything. Namur is a good place to try it without paying Brussels prices.
Look for boulets à la liégeoise (meatballs in a thick sweet-and-sour syrup sauce), lapin à la kriek (rabbit in cherry beer), truite des Ardennes (Ardennes trout), and escavèche — a vinegared fish dish, originally a way of preserving the eel and trout caught in the Meuse. The local escargots de Namur are a regional pride.
The best concentration of restaurants is around Place du Marché aux Légumes and Rue des Brasseurs, both pedestrianised. For a fine-dining splurge, L'Espièglerie in the historic Hôtel de Tanneurs is reliable. For a snack and a beer, the brasseries along the Meuse quay are pleasant in summer.