COMBINE CORNMEAL AND CHILE POWDER IN A MEDIUM BOWL. ADD PORK, TOSSING TO COAT. REMOVE PORK FROM BOWL, RESERVING ANY REMAINING CORNMEAL MIXTURE. ADD PORK TO PAN; SAUTÉ 5 MINUTES OR UNTIL BROWNED. STIR IN REMAINING CORNMEAL MIXTURE; COOK 30 SECONDS, STIRRING CONSTANTLY. STIR IN TOMATILLOS, BROTH, CHILES, AND JALAPEÑO; BRING TO A SIMMER OVER MEDIUM-LOW HEAT. COOK 8 MINUTES OR UNTIL TOMATILLOS ARE TENDER. STIR IN ONIONS AND REMAINING INGREDIENTS; SIMMER 1 MINUTE.