Step 1: Prepare the Vegetable Filling

1. Heat the Oil: In a large skillet or Dutch oven, heat the olive oil over medium heat. Allow the oil to shimmer slightly, indicating it’s hot enough.
2. Sauté Aromatics: Add the diced yellow onion to the skillet and sauté for 5-7 minutes, or until softened and translucent. Stir occasionally to prevent sticking and ensure even cooking.
3. Add Garlic and Peppers: Add the minced garlic, diced red bell pepper, and diced green bell pepper to the skillet. Sauté for another 5-7 minutes, or until the peppers are slightly softened but still retain a bit of crispness. Stir regularly.
4. Incorporate Zucchini: Add the diced zucchini to the skillet and sauté for 3-5 minutes, or until it begins to soften. Zucchini cooks quickly, so don’t overcook it at this stage.
5. Season and Spice: Stir in the chili powder, cumin, and smoked paprika. Cook for 1 minute more, stirring constantly, until fragrant. This step blooms the spices and enhances their flavor.
6. Add Beans, Corn, and Spinach: Add the rinsed and drained black beans, drained corn kernels (or frozen corn), and squeezed-dry spinach to the skillet. Stir everything together to combine thoroughly.
7. Season to Perfection: Season the vegetable mixture with salt and black pepper to taste. Start with about 1 teaspoon of salt and 1/2 teaspoon of black pepper, and adjust as needed. Taste and add more seasoning if desired.
8. Simmer and Reduce: Reduce the heat to low and simmer for 5-10 minutes, allowing the flavors to meld together and the excess moisture to evaporate. This step is crucial for preventing watery enchiladas. Stir occasionally.
9. Remove from Heat: Once the filling is heated through and slightly thickened, remove the skillet from the heat and set aside.

Step 2: Assemble the Enchiladas

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Warm Tortillas (Optional but Recommended): Warming the tortillas makes them more pliable and prevents them from cracking when rolled. You can warm them in a few ways:

   • Microwave: Stack the tortillas, wrap them in a damp paper towel, and microwave for 30-60 seconds until softened.
   • Skillet: Heat a dry skillet over medium heat. Warm each tortilla for about 15-20 seconds per side, until softened.
   • Oven: Wrap the tortillas in foil and warm in the preheated oven for 5-10 minutes.

3. Sauce the Bottom of the Baking Dish: Pour about 1/2 cup of enchilada sauce into the bottom of a 9×13 inch baking dish or casserole dish. Spread the sauce evenly to prevent the enchiladas from sticking and add moisture.
4. Fill and Roll Enchiladas: Take a warmed tortilla and spoon about 1/3 to 1/2 cup of the vegetable filling down the center. Don’t overfill, or the enchiladas might be difficult to roll and may burst.
5. Roll Tightly: Roll the tortilla up tightly, like a burrito, and place it seam-down in the prepared baking dish. Arrange the enchiladas side-by-side in the dish. Repeat with the remaining tortillas and filling.
6. Top with Sauce and Cheese: Pour the remaining enchilada sauce evenly over the rolled enchiladas, ensuring they are well coated. Sprinkle the shredded cheese generously over the top of the sauce.

Step 3: Bake and Serve

1. Bake in Preheated Oven: Bake in the preheated oven for 20-25 minutes, or until the cheese is melted, bubbly, and lightly golden brown, and the enchiladas are heated through.
2. Rest Briefly: Remove the baking dish from the oven and let the enchiladas rest for 5-10 minutes before serving. This allows them to set slightly and makes them easier to serve.
3. Garnish and Serve: Garnish with your favorite toppings, such as sour cream, guacamole, chopped cilantro, sliced green onions, black olives, or pickled jalapeños. Serve hot and enjoy!