Grilled Barbecue Beef

• 3 tablespoons packed dark brown sugar
• 2 teaspoons ground cumin
• 2 teaspoons chili powder
• 1 1/2 teaspoons salt
• 1 teaspoon black pepper
• 1 teaspoon dry mustard
• 1 (1 1/4 -pound) flatiron steak (1 inch thick; also called boneless chuck top blade steak)
• 1 medium onion, finely chopped
• 1 tablespoon vegetable oil
• 1/2 cup ketchup
• 2 tablespoons Worcestershire sauce
• 5 tablespoons water

1. Stir together brown sugar, cumin, chili powder, salt, pepper, and mustard in a bowl. Pat steak dry and rub all over with 2 tablespoons spice mixture. Reserve remainder for sauce. Marinate steak at room temperature while making sauce.
2. Cook onion in oil in a 1- to 1 1/2-quart heavy saucepan over moderately high heat, stirring, until golden brown, 5 to 10 minutes. Stir in ketchup, Worcestershire sauce, and reserved spice mixture and bring to a boil over moderately high heat, stirring occasionally. Reduce heat and cover, then simmer until onions are very tender, about 5 minutes. Transfer to a blender and puree with water (use caution with hot liquids) until very smooth (add additional water, 1 tablespoon at a time, if necessary), then transfer to a bowl.
3. Meanwhile, preheat gas grill burners on high, covered, 10 minutes, then reduce heat to moderately high.
4. Oil grill rack, then grill steak, covered, 4 to 5 minutes per side for medium-rare. Brush steak all over with some of sauce and grill 30 seconds per side.
5. Transfer to a cutting board and let stand 5 minutes. Cut steak into thin slices and serve with remaining sauce.

brown sugar, ground cumin, chili powder, salt, black pepper, mustard, flatiron steak, onion, vegetable oil, ketchup, worcestershire sauce, water

Taken from www.epicurious.com/recipes/food/views/grilled-barbecue-beef-238392 (may not work)