Tortilla Pie

4 flour tortillas (10-inch)
1 tablespoon olive oil , plus more for pan
1 medium onion , chopped
1 1/2 teaspoons ground cumin
1/4 teaspoon red-pepper flakes
Coarse salt and ground pepper
2 tablespoons tomato paste
1 pound ground beef sirloin
3 garlic cloves , minced
1 package (10 ounces) frozen corn kernels
3 packed cups loose baby spinach (about 5 ounces) , torn into pieces
1 15-oz can black beans
2 cups (8 ounces) shredded Monterey Jack cheese

Preheat oven to 400 degrees. Using a paring knife, trim tortillas to fit a springform pan (use the removable bottom of the pan as a guide). Assemble pan with the bottom upside down; lightly oil bottom and sides. Set aside.

In a large skillet, heat oil over medium. Add onion, cumin, and red-pepper flakes; season with salt and pepper. Cook until onion has softened, 3 to 5 minutes. Stir in tomato paste. Raise heat to medium-high; add beef and garlic. Cook, breaking up meat with a spoon until no longer pink, 4 to 6 minutes.



Add corn and spinach; stir until spinach has wilted, about 2 minutes.







Then add black beans and stir.



Place one tortilla in the prepared pan. Spreading evenly, top with 1 1/2 packed cups beef mixture, then 1/2 cup cheese.





Repeat with two more layers. Top with last tortilla, and sprinkle with remaining 1/2 cup cheese.



Bake pie until top is lightly browned, 15 to 20 minutes. Run knife around edge of pan; remove sides. Using two wide metal spatulas, lift pie from bottom of pan, and transfer to a cutting board. Cut into wedges. If desired, serve with cilantro and sour cream.



Adapted from Martha Stewart