Slow-Cooker Barbecued Beef Brisket

Combine sugar, 2 tablespoons chipotle, cumin, paprika, 1 teaspoon salt, and 2 teaspoons pepper in bowl. Using fork, prick brisket all over. Rub sugar mixture over brisket, wrap tightly in plastic wrap, and refrigerate for 8 to 24 hours.

Microwave onions, tomato paste, garlic, oil, chili powder, and remaining 1 tablespoon chipotle in bowl, stirring occasionally, until onions are softened, about 5 minutes; transfer to slow cooker. Stir in water. Unwrap brisket and nestle fat side up into slow cooker. Spoon portion of onion mixture over brisket. Cover and cook until beef is tender, 9 to 10 hours on low or 6 to 7 hours on high.

Transfer brisket to carving board, tent loosely with aluminum foil, and let rest for 20 minutes.

Using large spoon, skim fat from surface of sauce. Whisk in ketchup, vinegar, and liquid smoke. Season with salt and pepper to taste. Slice brisket against grain into ½-inch-thick slices and arrange on serving dish. Spoon 1 cup sauce over brisket and serve, passing remaining sauce separately.