Making your own BBQ sauce is easy and well worth the effort. Slideshow: More Backyard Barbecue Essentials
In a medium saucepan, heat the oil over medium heat until hot, then stir in the onion, garlic 1 teaspoon salt and 1/2 teaspoon pepper. Cook, stirring until the onion is translucent, about 4 minutes. Stir in the tomato paste and cook, stirring until several shades darker, about 3 minutes. Stir in the chili powder and cook, stirring, 1 minute. Stir in the ketchup, water and vinegar and simmer until slightly thickened, about 15 minutes. Let BBQ sauce cool.
Preheat the oven to 425°F.
Place chicken on a baking sheet and brush with some of the BBQ sauce. Bake the chicken 15 minutes, then brush with more sauce. Bake the chicken another 15 minutes, then brush with more sauce. Continue baking the chicken until it is cooked through, 10 to 15 minutes more for a total roasting time of 40 to 45 minutes. Let cool and serve with remaining BBQ sauce on the side.