I completely pulled this recipe out of my rump and did it to taste. Normally you would make au jus from meat drippings but since I grilled the meat, I was not be able to catch the drippings (although I did toss in what I could gathered from when we cut up the meat).
64 oz. beef broth
2-3 Tbsp. minced garlic (depending how much you like garlic :D )
2 sticks of rosemary
2 Tbsp. Worcestershire
1. Combine all ingredients
2. Boil for a few minutes to reduce slightly.
3. Dip meat into au jus before eating.
4. Stuff face.