Set oven to 300 degrees Fahrenheit. Place onions on a piece of aluminum foil on top of a baking sheet. Drizzle with two tablespoons red wine, olive oil, brown sugar and salt. Wrap up the sides of the foil to create a pouch. Cook at 300 degrees for two hours.

Meanwhile, place the London broil, red wine, red wine vinegar, soy sauce, and honey in a plastic bag. Allow to marinate while onions are cooking.

When the onions are done, turn oven to broil on high.

Place the London broil on the baking sheet, and drizzle with about half of the marinade. Cook for five to seven minutes. Remove from oven, flip, and drizzle with remaining marinade. Return to oven for another five to seven minutes. Use a meat thermometer to determine if it is cooked to your liking.

Remove from oven and allow to rest for 10 minutes. Serve by cutting thin slices against the grain and topping with onions.