Heat 2 teaspoons oil in 12-inch skillet over medium-high. Cook zucchini with 1/4 teaspoon salt 5 to 6 minutes, turning occasionally, until browned and barely tender. Transfer to bowl.
Add remaining oil, beef, and onion; cook 7 to 8 minutes, crumbling beef, to 160°F. Spoon off excess fat.
Stir in garlic, paste, cumin, ancho chile, oregano, and remaining salt 1 minute. Add broth and corn; simmer 3 to 4 minutes until corn hot and sauce coats beef.
Return zucchini; warm 1 minute. Scatter Pepper Jack; cover over low 2 minutes until melted.
Remove from heat; drizzle lime juice. Divide among 4 bowls.