In a large skillet, heat 2 tablespoons of the olive oil. Add the garlic and cook over moderate heat until golden, 3 minutes. Add the cauliflower and cook, stirring, until well coated with the garlic and just starting to soften, 3 minutes. Add the flour and toss to coat. Stir the cauliflower into the soup, cover partially and continue to cook over moderately low heat, stirring occasionally, until the cauliflower is tender, 15 minutes.