You can make vegetable soups rich and smooth without using flour or cream. Puree half of the cooked vegetables in your blender or food processor, then add to the soup.
Preheat oven to 450 degrees. On a baking sheet, toss cauliflower with vegetable oil and 1 teaspoon salt. Spread out, and roast until the florets turn brown, about 25 minutes.
In a medium saucepan, melt butter over medium-high heat. Add onions, and cook until soft, about 5 minutes. Stir in curry powder, cauliflower, water, and broth; cover, and bring to a boil. Uncover, lower heat, and simmer 5 minutes.
Using a slotted spoon, transfer 3 cups cauliflower to a bowl, and set aside. Put remaining florets into a blender or food processor, add 1 teaspoon salt, and process until smooth. Stir puree into broth in pan, and reheat if necessary. Ladle soup into bowls, and top with reserved florets and parsley.
Serve this soup with toasted ham or cheese sandwiches on whole-grain country bread.