The title takes almost as long to read as it takes to eat it!!! Hahahahahaah
1) Place vegetable oil in a large nonstick skillet and add the sliced onions. Sauté over low heat, stirring often, until onions are golden brown, soft and caramelized. Do not let burn.
2) Season to taste with salt and pepper, and stir in the hot mustard. Set aside.
3) Prepare a grill, and cook sausages, basting with the beer every minute or so.
Serve the sausages with the mustard-seasoned onions.