Instructions

Place 24 corn husks in large bowl and cover with hot water; soak until pliable, about 30 minutes. Combine 1½ tablespoons chili powder, 1 tablespoon paprika, 1 tablespoon salt, 2 teaspoons ground cumin, 2 teaspoons sugar, ¾ teaspoon pepper, and ¾ teaspoon cayenne pepper in bowl.
Pulse 2½ cups (12½ ounces) yellow cornmeal and 1 tablespoon baking powder in food processor until combined, about 3 pulses. Add 12 tablespoons unsalted butter, cut into 12 pieces, and 1½ tablespoons spice mixture and pulse to chop butter into small pieces, about 8 pulses. Add 1¼ cups water and process until dough forms, about 30 seconds. Reserve ½ cup cornmeal mixture. Divide remaining cornmeal mixture into 24 equal portions, about 1½ tablespoons each, and place on plate.
Dissolve ½ teaspoon baking soda in 2 tablespoons water in large bowl. Add 1 pound ground beef, 2 minced garlic cloves, reserved ½ cup cornmeal mixture, and 1½ tablespoons spice mixture and knead with your hands until thoroughly combined. Divide meat mixture into 24 equal portions, about 1½ tablespoons each, and place on plate.
Remove husks from water and pat dry with dish towel. Working with 1 husk at a time, lay husk on counter, smooth side up, with long side parallel to counter edge and wide end oriented toward right. Using small offset spatula, spread 1 portion of cornmeal mixture in 3½-inch square over lower right corner of husk, flush to bottom edge but leaving ¼-inch border on right edge.
Place 1 portion of meat mixture in log across center of cornmeal (end to end), parallel to long side of husk. Roll husk away from you and over meat mixture so cornmeal mixture surrounds meat and forms cylinder; continue rolling to complete tamale. Fold tapered end (left side) of tamale up leaving top open. Using scissors, trim tapered end of tamale to align with filled end (if tapered end hangs over). Set tamales aside seam side down.
Stack tamales on their sides in groups of 6 and tie into bundles with kitchen twine. 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 5½ cups water to pot to come within 1 inch of tops of tamales, being careful not to pour water into tamales.
Bring water to boil. Cover, reduce heat to low to maintain gentle simmer, and cook until tamales are firm and beginning to pull away from husks, about 30 minutes. Using tongs and slotted spoon, carefully transfer tamales to serving platter and remove twine.
Return liquid to simmer over medium heat. Combine 2 tablespoons cornstarch with 2 tablespoons cold water in small bowl. Whisk in cornstarch slurry and cook until slightly thickened, about 1 minute. Serve sauce with tamales.