Step 1

Preheat oven to 375°F. Heat a medium (10-inch) ovenproof skillet (preferably cast iron) over medium. Add oil, poblano, and 1 cup onion; season with salt and pepper. Cook, stirring occasionally, until onion is translucent, about 5 minutes. Add zucchini; continue cooking until vegetables are tender and golden in places, 10 to 12 minutes more.

Step 2

Remove from heat; transfer mixture to a large plate. Pour 1 cup salsa into skillet. Working one at a time, dip tortillas in salsa, turning to evenly coat both sides; transfer to plate with vegetables.

Step 3

Layer tortillas and vegetables evenly in skillet. Top evenly with mozzarella, crema, and remaining 1/2 cup salsa. Bake until bubbly and browning in places, 20 to 22 minutes. Serve with lettuce, radishes, tomatoes, and remaining 1/4 cup onion.