Fresh tomatillos come in papery husks, which peel off easily to reveal what looks like small green tomatoes. They have a tart lemony flavor and must be cooked before eating; a brief stewing will mellow the flavor while leaving some of the characteristic tang.
Heat oil in a large nonstick skillet over medium-high heat.
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.