1. For Cauliflower: Adjust oven rack to lowest position and heat oven to 475°F. Trim outer leaves of cauliflower and cut stem flush with bottom. Cut head into 8 equal wedges so that core and florets remain intact (see illustration). Place wedges cut side down on foil or parchment-lined rimmed baking sheet. Drizzle with 2 tablespoons oil and sprinkle with salt and pepper; gently rub to evenly distribute oil and seasonings. Gently flip cauliflower and season other cut side with 2 tablespoons oil, salt, and pepper.

2. Cover baking sheet tightly with foil and cook for 10 minutes. Remove foil and continue to roast until bottoms of cauliflower pieces are golden, 8 to 12 minutes. Remove sheet from oven, and using spatula, carefully flip wedges. Return sheet to oven and continue to roast until cauliflower is golden all over, 8 to 12 minutes longer.

3. For Sauce: While cauliflower roasts, heat vegetable oil in small skillet over medium-high heat until shimmering. Add garlic and ginger; cook until fragrant, about 1 minute. Reduce heat to medium-low and add soy, mirin, vinegar, and water. Simmer until slightly syrupy, 4 to 6 minutes. Drizzle sauce and sesame oil over roasted cauliflower and garnish with scallions.

Serves 4 to 6