In a 4- to 5-quart nonstick pan over high heat, stir serrano chilies, cumin, onion, and chicken until meat is crumbled and onion is limp, about 8 minutes.
Add beans, milk, and corn. Stir just until hot, 1 to 2 minutes.
Ladle into wide bowls. Sprinkle with ground chili and season with salt to taste. Serve with lime wedges to squeeze over portions.