In a large pot or deep skillet cook the bacon over medium high heat. Remove the bacon from pot, chop and set aside. Pour off about half of the bacon grease, leaving about 1 tablespoon still in the pan.
Add the butter and cook until melted.
Add the onions, cook until slightly browned.
Stir in the garlic, then add the tomatoes, jalapenos, red pepper flakes, beer, lime juice and chopped bacon. Bring to a low simmer.
Add the mussels, cover and allow to cook until mussels have opened, about 5 minutes.
Discard any that didn’t open. Sprinkle the green onions over the pan.
Serve with crusty bread.