La Ducasse
A bit out of the old center you'll find this nice small restaurant. This place is always well visited and they serve simple though tastful food. The red and brown colors provide a nice atmosphere.
Address: 95, Rue Solférino, tel.: 03 20 57 34 10

Brasserie Aux Moules
This brasserie is located in one of the main shopping streets of Lille and it's supposed they sell the most mussels in France. So only go to this large restaurant if you like these 'moules'.
Address: 34, rue de Béthune, tel.: 03 20 57 12 46