Preheat the oven to 350°F (175°C).

In a large skillet, heat the olive oil over medium-high heat.

Add the portobello mushrooms and diced onion to the skillet, and sauté for approximately 6-7 minutes, until they soften.

Stir in the minced garlic cloves and cook for an additional 30 seconds, or until fragrant.

Add the fresh spinach, salt, cumin, and black pepper to the mixture, and stir to combine. Cook until the spinach has wilted, which should take about 5 minutes.

Drain any excess liquid from the mixture.

Remove the skillet from heat and stir in the vegan sour cream until it evenly coats the spinach and mushroom filling.

To assemble the enchiladas, spoon about 2 tablespoons of the spinach and mushroom filling onto a flour tortilla, then roll it up tightly. (If the tortillas are too stiff and dry to roll without cracking, wrap them in a damp towel and warm them in the microwave for a few seconds.)

Place the rolled enchilada seam side down in a baking dish. Continue filling and rolling the remaining tortillas until all the enchiladas are assembled.

Pour the enchilada sauce over the top and sprinkle with vegan shredded cheese.

Bake in the preheated oven until heated through and the cheese is melted, approximately 20-25 minutes. Enjoy!