Preheat the oven to 400 degrees. Drizzle 1 tablespoon of the oil onto a baking sheet. Sprinkle on the turmeric. Spread the cauliflower on the pan in one layer. Drizzle with the remaining oil. Add the salt and several grinds of pepper. Mix with your hands to coat the florets.
Roast for 20 minutes. Stir the cauliflower, roast 5 minutes and stir again. Continue roasting until the cauliflower is almost soft and some tips are dark brown, about 5 minutes longer. Cool the cauliflower on the pan. Serve warm or at room temperature.