Ancho chile powder gives the meat its southwestern flavor. Chef Purviance suggests serving the brisket with southwestern-style coleslaw (sliced cabbage, jicama, and red onions tossed in a red-wine vinaigrette) and black beans with corn, tomatoes, and chiles. Leftovers would make great sandwiches
4 teaspoons coarse kosher salt
1 tablespoon (packed) golden brown sugar
2 teaspoons ancho chile powder
1 teaspoon paprika
1 teaspoon ground cumin
1 teaspoon granulated garlic
1 teaspoon coarsely ground black pepper
1 5- to 5 1/2-pound flat-cut (also called first-cut) brisket with 1/4- to 1/2-inch layer of fat on 1 side
4 cups hickory or oak wood chips, soaked in water 1 hour
4 disposable 6 x 3 3/4 x 2-inch mini aluminum loaf pans (for wood chips, if using gas grill)
2 11 3/4 x 8 1/2 x 1 1/4-inch disposable aluminum pans (for brisket)
Ancho Chile Sauce
Mix first 7 ingredients in small bowl.
Rub spice blend over brisket. Wrap brisket in plastic; refrigerate at least 2 hours and up to 24 hours.
Remove top rack from barbecue. Prepare barbecue (low heat). Light briquettes in chimney; pour onto 1 side of lower grill rack (you’ll need to light more briquettes in chimney to replenish 2 or 3 more times during grilling). Drain 2 cups wood chips. Scatter 2 cups wood chips over coals. Return grill rack to barbecue. Heat barbecue to 300°F.
Remove top rack from barbecue. Prepare barbecue (low heat). If using 2-burner grill, light 1 burner. If using 3-burner grill, do not light center burner. Drain 2 cups wood chips. Stack 2 mini loaf pans(one inside the other); fill with 1 cup wood chips. Stack remaining loaf pans; fill with 1 cup wood chips. Place pans over flame (if using 3-burner grill, place both pans on 1 lit side). Return rack to barbecue. Heat barbecue to 300°F. (If temperature rises too high on 3-burner grill, turn off burner without chips.)
Unwrap brisket and arrange fat side up in 11 3/4 x 8 1/2 x 1 1/4-inch aluminum pan; place pan over unlit part of barbecue. Cover barbecue. Cook brisket until instant-read thermometer inserted into center registers 160°F, adjusting vents or adding more charcoal as needed (if using charcoal grill) or adjusting gas levels (if using gas grill) to maintain temperature inside barbecue grill at 250°F, about 3 1/2 hours. Baste brisket occasionally with pan juices and add more drained wood chips as needed.
Remove pan with brisket. Discard pan and juices. Wrap brisket tightly in 2 wide sheets of heavy-duty foil. Place in clean 11 3/4 x 8 1/2 x 1 1/4-inch aluminum pan. Return to grill over unlit side, maintaining temperature inside grill at 250°F, until instant-read thermometer inserted into thickest part of center of brisket registers 190°F, about 1 1/2 hours longer. Transfer brisket in pan to rimmed baking sheet. Let rest at least 1 hour and up to 2 hours.
Carefully unwrap brisket, saving any juices in foil. Transfer juices to small pitcher. Place brisket on work surface. Thinly slice brisket across grain; transfer to platter. Brush brisket with some of juices. Serve with any remaining juices and Ancho Chile Sauce.