Trim the broccoli and cauliflower and chop coarsely. The core of the cauliflower and the broccoli should be used too. Save a few tiny florets of broccoli to add later. In a large pot, heat the oil over medium heat. Add the garlic and sizzle until it smells fragrant. Add the broccoli, cauliflower, stock and salt. Bring to a boil, turn down and cook at a lively simmer until the vegetables are tender, about 20 minutes. Puree in batches in a food processor or blender - a blender works best for this - with the mustard and tarragon add the broccoli florets and season to taste. Thin with stock or water if the soup is too thick. Add the cream if desired. The dairy is optional and not included in the count. Total Calories: 566 Fat: 31 grams Carbs: 63 grams (5.25 per cup) Fiber: 33 grams Protein: 31 grams