Boil 1-cup water. Pour saffron into the boiling water and steep for 10-15 minutes. Meanwhile, bring remaining water to a boil in a saucepan. Add the saffron water, sea salt and cauliflower; cook, covered, for 10 minutes. Drain, but reserve cooking liquid for later use. In a heavy-bottomed saucepan, melt butter over moderate heat. Add the flour and mix well. Cook, stirring, for a minute or two. Whisk in the cauliflower water reserved from the previous step. Bring to boil, stirring constantly, and then reduce heat. Stir until the sauce reaches desired thickness. Season with salt and pepper to taste, toss with cauliflower and heat through.