Preheat oven to 475°. Bring wine, oil, kosher salt, juice, butter, red pepper flakes, sugar, bay leaf, and 8 cups water to a boil in a large pot. Add cauliflower head, reduce heat, and simmer, turning occasionally, until a knife easily inserts into center, 15-20 minutes.
Using 2 slotted spoons or a mesh spider, transfer cauliflower to a rimmed baking sheet, draining well. Roast, rotating sheet halfway through, until brown all over, 30-40 minutes.