The Restaurant at Auberge Saint-Pierre
The restaurant at Auberge Saint-Pierre is mentioned by professionals. Out of 3 publications tracked on TripExpert, 3 praised the restaurant, including Frommer's, Oyster and Fodor's.
Auberge Saint-Pierre 
Frommer's
Oyster
Fodor's
Frommer's "The restaurant is just as charming, with set menus from 20€ to 65€, which include agneau du pré salé, local lamb raised on salt marshes, and the especially fluffy Mont-St-Michel omelet"
Oyster "Like many of the other hotels on Mont Saint-Michel, the Auberge has an expensive restaurant that receives mixed reviews"
Fodor's "This inn is a popular spot due to the fact that it’s in a half-timber 15th-century building adjacent to the ramparts and has its own garden restaurant (half-board rates are available)"
