How to Make It
Preheat a 12-inch cast-iron skillet over high heat for 5 minutes, Add the oil, then the carrots. Stir to coat the carrots with oil and cook, stirring frequently, until the carrots are partially charred, about 15 minutes.
Reduce the heat to moderate and add the shallots, garlic and thyme. Cook until the shallots are softened, 2 to 3 minutes.
Add the potato and stock. Simmer over low heat until the carrots and potato are very soft, about 15 minutes.
In a food processor or blender, puree the soup until smooth. (For an extra silky texture, press the puree through a fine sieve after pureeing.)
Transfer the soup to a saucepan and add the cream (use extra chicken stock or water for a thinner consistency it desired). Add the red wine vinegar, salt and pepper. Stir in the butter and serve hot, sprinkled with the chopped parsley.