Preheat the oven to 425°F and position a rack in the center. In a large mixing bowl, whisk together the oil, chili powder, garlic powder, paprika, oregano, cumin, and 1 1/2 teaspoons of kosher salt until well combined. Add the cauliflower florets to the bowl and toss thoroughly to ensure each piece is evenly coated in the seasoned oil mixture.
Arrange the cauliflower florets cut side down on a foil-lined baking sheet, spreading them out in a single layer. Roast for 25 to 30 minutes, or until the cauliflower is deeply caramelized on the bottom and fork-tender at the center. Remove from the oven and allow it to cool for 5 minutes directly on the baking sheet.
While the cauliflower roasts, prepare the crema. In a small bowl, mix the vegan sour cream with 1 tablespoon of fresh lime juice and 1/2 teaspoon salt. Stir until smooth, then cover and refrigerate until ready to assemble the tacos.
In another bowl, combine the red cabbage, white cabbage, red onion, 1/4 cup chopped cilantro, the remaining 2 tablespoons of lime juice, and the remaining 1/2 teaspoon of salt. Toss well and set aside at room temperature to allow the flavors to meld.
To assemble the tacos, spoon a generous portion of slaw into each warmed corn tortilla. Add three to four roasted cauliflower florets on top, followed by a drizzle of lime crema. Sprinkle with additional cilantro for a fresh burst of flavor and color. Serve immediately with lime wedges on the side for squeezing.
