In a large pot over a medium heat, add the Grolsch, bay leaves and garlic. Bring to a simmer before adding the cleaned mussels and covering with a lid. After 5 minutes the mussels should have opened. Discard any at this point that have not opened.
Remove the mussels and add them to a serving dish. Stir the wholegrain mustard into the remaining liquid in the pot.
Pour the liquid over the mussels and serve with crispy bread.
For more pairing ideas, visit our dedicated Grolsch page.