Preheat oven to 400°. Wash florets and cut into smaller, bite-size pieces where necessary.

Line a large, rimmed baking sheet with aluminum foil and drizzle with 1 tablespoon oil. Spread florets onto sheet and drizzle with remaining oil. Sprinkle with sea salt, red pepper flakes, and shredded ginger. Toss to coat evenly.

Roast until lightly browned and crispy, stirring often so as not to burn, about 20–25 minutes. When done, florets should not wilt or sag when lifted. Serve warm or cold.