Preheat the oven to 350°F (175°C) and lightly oil a 9×11-inch baking dish.
Heat 1 teaspoon olive oil in a large skillet over medium heat. Add the minced garlic and diced red onion and sauté until the onion is translucent, about 5 minutes.
Add the chopped portabella mushrooms, chopped green bell pepper, chopped spinach, and sliced black olives to the skillet and sauté until the vegetables are softened, about 5–7 minutes.
Stir in the 14-oz can tomato sauce and 1/2 cup water. Add turmeric, smoked paprika, chili powder, and agave nectar; season with salt and pepper to taste. Reduce heat to low, cover, and simmer a few minutes to meld flavors.
While the filling simmers, make the avocado-cilantro cream. Place avocado flesh, 2 tablespoons lime juice, 1/4 cup canned coconut milk, 1/2 cup water, 1 1/2 cups packed cilantro, 1 teaspoon salt, and 1/4 teaspoon pepper in a blender or food processor and blend until smooth.
Spread a thin layer of the avocado-cilantro cream on one side of each corn tortilla.
Assemble the lasagna: pour half of the vegetable-tomato filling into the bottom of the prepared baking dish and spread evenly. Place 5 of the cream-coated tortillas over the filling in a single layer.
Spread the remaining vegetable filling over the tortillas, then top with the remaining 5 cream-coated tortillas.
Cover the dish with foil and bake for 25 minutes. Remove from the oven and let sit a few minutes, then garnish with sliced green onion and chopped cilantro before serving.
