On a tray place the previously peeled and cut carrot, the tomatoes, the onion and the garlic. Drizzle with a little olive oil and season to your liking.
Bake for 15 min.
Put everything on the tray in a blender, add the basil, the vegetable broth, the milk, the sour cream and blend until it takes on a smoother consistency.
In a frying pan or pot, put the butter and when it is melted add the mixture and cook for 10 minutes until it boils, season it.