Beer-Barbecue Mussels with Garlic Bread

2 pounds mussels

2 tablespoons unsalted butter

1 onion, diced

1 cup dark beer

1 cup prepared BBQ sauce

4 cloves garlic, minced

Salt and pepper to taste

Sliced green onions, for garnish

Serve with garlic bread

Rinse mussels under cold water and remove any beards. If any are open, tap them on the counter. If they do not close, discard them. 

In a large skillet with a lid, melt butter over medium-high heat. Add onion and cook until translucent, about 3 minutes. Stir in beer and BBQ sauce and season with salt and pepper. Bring to a boil. Add mussels, toss to coat with sauce and cover. Let steam until mussels are open, about 6 minutes.  

Discard any mussels that have not opened. Transfer to a serving bowl and pour pan liquid over. Garnish with green onions and serve.