Brooklyn Style Sausage and Peppers

1. Heat a heavy skillet over medium heat. Add about 2 tablespoons of olive oil and a tablespoon of butter. Add as many of the sliced onions as will comfortably fit in the skillet (we are going to caramelize the onions, so don’t crowd them too much). Sprinkle with salt and freshly ground black pepper and sauté the onions, in batches, until they are nicely browned (caramelized). Remove the caramelized onions to a bowl and repeat the procedure with the next batch. Continue, adding additional oil and butter as necessary, until all the onions are cooked.
2. In the same skillet as the one the onions were cooked in, cook the peppers in a similar manner, but don’t brown the peppers as much.
3. When all the peppers and onions have been cooked, return them both to the skillet. Mix the onions and the peppers together so they are evenly distributed. Stir about 2 tablespoons of balsamic vinegar into the mixture and cook, stirring, for about a minute or two to allow the balsamic to flavour the entire mixture. Remove the onion and pepper mixture to a large bowl.
4. Heat a grill (or cast iron skill) over medium heat, place the sausages on the grill and cook until they are richly browned on all sides. When the sausages are cooked, re-warm the onion and pepper mixture and distribute it on a serving platter. Place the cooked sausage on top of the mixture.
5. The sausage, peppers, and onions can either be served on a plate and eaten with a knife and fork, over pasta as a sauce (add water or chicken broth in step 3 to thin the sauce out), or they can be served as they are in Brooklyn at Italian feasts: by slicing the rolls down the middle, placing a sausage in the slit and covering it with the onion and pepper mixture, hot dog style.