Prepare the Cauliflower - Preheat the oven to 425°F (220°C). Toss the cauliflower florets with rice vinegar, soy sauce, and garlic powder in a mixing bowl. Sprinkle cornstarch over the florets and mix until evenly coated.
Roast the Cauliflower - Spread the cauliflower florets in a single layer on a baking sheet lined with parchment paper. Roast in the preheated oven for 20-25 minutes, or until the cauliflower is crispy and golden brown, flipping halfway through cooking.
Coat in Buffalo Sauce - In a saucepan, heat the buffalo sauce over low heat. Once the cauliflower is roasted, transfer it to a mixing bowl and pour the warm buffalo sauce over the florets. Gently toss until all the florets are coated.
Assemble the Bahn Mi - Slice the baguettes horizontally, but not all the way through. Spread mayonnaise on one side of each baguette. Place a generous amount of buffalo cauliflower on the other side. Top with pickled vegetables and chopped cilantro.
Serve and Enjoy - Serve the Buffalo Cauliflower Bahn Mi immediately, and savor the crispy, spicy, and tangy flavors. Pair it with your favorite side salad or enjoy it on its own for a deliciously satisfying meal.