Salt the bone barrow bones and roast at 400 degrees for one hour. Once the bones are done, add them to a pot with the carrots, 1/2 onion, celery, and peppercorns. Top with 8 cups of water and bring to a boil. Once boiling, simmer for at least 3 hours. Once the broth is done, chop your onions and saute in olive oil until translucent. Add worchestershire and balsamic vinegar and continue to cook down. Once caramelized, add 4 cups of broth and 1 cup of wine. Add white wine fora traditional French Onion Soup, and red wine for a heartier, more full-bodied flavor. Bring up to a boil, htne simmer for 3-5 minutes. Serve over a piece (or two!) of sourdough bread and top with gruyere cheese. I used a blowtorch to melt and brown the cheese, but a broiler works quicker and even better. Enjoy!