Preheat the oven to 435F (220C).In a large bowl, toss the cauliflower florets with 2 tablespoons of the olive oil until evenly coated. Sprinkle with the chili powder, paprika, coriander, cumin, red pepper flakes, and a generous pinch of salt. Toss again until the cauliflower is evenly coated. Spread the cauliflower on a rimmed baking sheet.Bake for 20 minutes, until crispy.Heat the remaining 2 tablespoons of olive oil in a large skillet over medium heat. Add the onion, poblano, and red bell pepper and saute until the onion is tender and a bit golden, about 15 minutes. Add the garlic and saute for another minute. Stir in the mushrooms, then season with salt and pepper. Cook until the mushrooms are tender and crispy (5 to 8 minutes). Remove from the heat and stir in the lime juice. Taste and adjust seasonings as desired.For each taco, put 1/4 cup (60ml) of the mushroom mixture in a tortilla. Top with some of the roasted cauliflower and a tablespoon of cilantro.Optional: top with avocado slices and hot sauce, to your liking.