1 Combine Cauliflower And Water Or Stock In A Medium Saucepan, Bring To A Boil Over High Heat. Reduce Heat To A Simmer, And Cook Until Cauliflower Is Very Tender, About 10 Minutes. 2 Transfer Cauliflower To A Blender Using A Slotted Spoon. Add A Few Tablespoons Of The Cooking Liquid And Blend Until Smooth, About 15 To 20 Seconds. Add Sour Cream And Butter, And Blend 5 To 10 Seconds More. Season With Salt And Pepper. Serve Hot.