1. Combine chili powder, paprika, salt, cumin, sugar, pepper, and cayenne in bowl. Pulse cornmeal and baking powder in food processor until combined, about 3 pulses. Add butter and 1 1/2 tablespoons spice mixture and pulse to chop butter into small pieces, about 8 pulses. Add 1 1/4 cups water and process until dough forms, about 30 seconds. Reserve 1/2 cup cornmeal mixture. Divide remaining cornmeal mixture into 12 equal portions, scant 1/4 cup each, and place on plate.

2. Dissolve baking soda in 2 tablespoons water in large bowl. Add beef, garlic, reserved 1/2 cup cornmeal mixture, and 1 1/2 tablespoons spice mixture and knead with your hands until thoroughly combined. Divide meat mixture into 12 equal portions, scant 1/4 cup each, and place on plate.

3. Working with 1 piece of parchment at a time, lay on counter with long side parallel to counter edge. Using small offset spatula, spread 1 portion of cornmeal mixture in 8 x 3-inch rectangle flush to bottom edge of parchment but leaving 2-inch border on left and right sides.

4. Place 1 portion of meat mixture in 8-inch log across center of cornmeal, parallel to long side of parchment. Roll parchment away from you and over meat mixture so cornmeal mixture surrounds meat and forms cylinder; fold in ends to close and continue to roll to complete tamale. Cut tamale in half to yield two 4-inch tamales and set aside seam side down.

5. Stack tamales on their sides in groups of 6. Tie each bundle with 2 pieces of kitchen twine spaced evenly apart. Add remaining 2 tablespoons spice mixture to large saucepan. Stand tamales, open ends up, in pot (walls of pot should clear tops of tamales). Add about 5 1/2 cups water to pot to come within 1 inch of tops of tamales, being careful not to pour water into tamales.

6. Bring tamales to boil. Cover, reduce heat to low to maintain gentle simmer, and cook until tamales are firm and beginning to pull away from parchment, about 30 minutes. Using tongs and slotted spoon, carefully transfer tamales to serving platter and remove twine.

7. Return liquid to simmer over medium heat. Whisk in cornstarch slurry and cook until slightly thickened, about 1 minute. Serve sauce with tamales.

Serves 6 to 8