The avocado and ranch help soften the spiciness of the roasted Buffalo cauliflower, which is perfectly tender and flavorful in these vegetarian tacos. The roasted corn adds some sweetness and the romaine some fresh, crisp, crunch.
Place rack in upper third of oven; preheat to 425°F. Line a large rimmed baking sheet with parchment paper. Combine cauliflower, Buffalo sauce and 2 tablespoons oil in a large bowl; toss well to coat. Spread in an even layer on the prepared baking sheet. Roast until the cauliflower starts to brown and is almost tender, 12 to 14 minutes. Remove from oven and sprinkle evenly with cheese. Continue roasting until the cauliflower is tender, 8 to 10 minutes. Set aside until ready to serve.
Heat a large nonstick skillet over medium-high heat. Add corn and the remaining 1 1/2 teaspoons oil; cook, stirring occasionally, until the corn is blistered and charred, about 5 minutes. Remove from heat.
Divide the cauliflower, lettuce, corn and avocado evenly among warm tortillas. Drizzle evenly with ranch dressing. Serve immediately.
Equipment: Parchment paper