Preheat oven to 450 degrees F (230 degrees C). Place the cauliflower in a small roasting pan. Drizzle with oil and season with salt, pepper, nutmeg, coriander seeds powder, toss to coat and distribute evenly.
Roast the cauliflower until tender for about 10 minutes, then remove from the oven and set aside.
Heat 2 tablespoons coconut oil in a large pot and add leeks, onion, carrots, garlic. Stir for about 5-7 minutes, until fragrant.
Add the roasted cauliflower and saffron. Stir for another 2 minutes.
Remove from heat and put all the soup ingredients in a blender, then puree.
Bring the puree soup back to the pot and add broth. Cook at low heat and bring to boil for about 10 minutes
Add salt/pepper to taste.
Remove from the heat and serve