Place the balsamic vinegar, olive oil, garlic and pepper flakes in a 1-gallon resealable plastic storage bag and add the rib-eyes. Allow to marinate at room temperature for up to 2 hours.
Preheat a grill to medium heat.
Remove the steaks from the marinade and season on both sides with the Essence and salt. Place the steaks on the grill and cook for 6 minutes on the first side, turning a quarter turn once after 3 minutes to make a crosshatch pattern. Turn the steak over and brush with 3 tablespoons of the barbecue sauce and continue to cook for an additional 5 to 6 minutes for medium rare. Remove from the grill and serve immediately.
Combine all ingredients thoroughly.
Recipe from "New New Orleans Cooking", by Emeril Lagasse and Jessie Tirsch, Published by William Morrow, 1993.
Set a 1-quart saucepan over medium heat and add the olive oil. Add the red onion and garlic and saute until the onions are lightly caramelized, about 5 to 7 minutes. Add the balsamic vinegar and brown sugar to the pan and bring to a boil. Continue to cook until the vinegar is nearly completely reduced, about 10 minutes. Add the red wine and reduce by half, about 5 minutes. Add the remaining ingredients and cook until the sauce is slightly thickened, about 7 to 8 minutes. Remove from the heat, discard the rosemary and puree using an immersion blender. Use immediately or store in an airtight plastic container in the refrigerator for up to 2 weeks.