Bring beer to a boil in a large, wide pot. Add sausages and onions and simmer 15 minutes. Cover, remove from heat, and let sit until ready to grill.
Heat a gas or charcoal grill to medium (you can hold your hand 1 to 2 in. above the cooking grate only 4 to 5 seconds). Using tongs or a slotted spoon, transfer sausages to the grill. Cook sausages, turning once, until browned on both sides, about 8 minutes. Meanwhile, drain onions and set aside. Serve sausages hot or warm, with onions if you like.
Note: Nutritional analysis is per serving.