Crockpot Roast Beef

3/4 cup Root beer (not diet!)

1/3 cup hickory-flavored barbecue sauce

2 tbsp tomato paste

1 tbsp freshly squeezed lemon juice 

1 tbsp freshly grated ginger root

2 tsp Worcestershire sauce

1 tsp minced garlic

1/2 tsp each ground cumin and chili powder

1 sirloin tip roast (3 to 3.5 pounds)

salt and pepper

2 tsp olive oil or veg oil

1 medium onion, cut into wedges

2 tbsp cornstarch

To make sauce, combine root beer, barbecue sauce, tomato paste, lemon juice, ginger root, Worcestershire sauce, garlic, cumin and chili powder in a small saucepan. Bring to a boil over medium-high heat. Reduce heat to medium and let sauce boil gently for 2 minutes. Remove from heat. The sauce is very strong and concentrated at this point - don't worry it will mellow out once it's cooked in the beef juices.

Pat roast dry and paper towels. Sprinkle lightly with salt and pepper. Heat oil in a large skillet or Dutch oven over medium-high heat. Add roast and brown it on all sides.

Place browned roast in a slow cooker. Arrange onion wedged around it. Pour sauce over roast. cover with lid and cook on low heat for 8 hours. 

Remove the roast and onions from the slow cooker (use a slotted spoon to scoop out the onions) Pour sauce from the crock pot into a medium saucepan. Skim off as much fat as possible. in a small bowl, mix cornstarch with an equal amount of water and stir until smooth. Add to sauce and bring to a boil over high heat, whisking constantly, until sauce has thickened slightly.

To serve, slice roast thinly.  Spoon the sauce over top.