- Preheat oven to 450 degrees. In a roasting pan, toss cauliflower pieces with half the oil and season with salt. Roast in oven for 10 minutes.
- In large pot, heat remaining oil. Add onions and cook over medium heat for 4 to 5 minutes. When onions just start to soften, add cauliflower and cook for an additional 5 minutes. Add wine to the pot to deglaze; cook until liquid is reduced, about 3 minutes. Add stock and bring to a low boil. Cover and cook for 20 minutes.
- Working in small batches, blend contents of the pot in blender for 2 minutes. Return soup to pot, season with salt and pepper, and keep warm over low heat.
- In a very hot pan, add chorizo and break into small pieces with a wooden spoon. Cook until sausage is dark brown and crispy. Reserve on a paper towel-lined plate.
- Serve soup garnished with chorizo crumbles and chopped chives.