Scald tomatoes with 500 ml of boiling water. Leave to stand for about 15 minutes. Peel onion and chop roughly. Peel, wash and slice the carrots. Peel, wash and chop the potatoes.
Heat the oil in a pot and sauté the onion. Add the potatoes and carrots, sauté briefly, sprinkle with 1 tbsp. sugar and sauté. Deglaze with broth, orange juice and tomatoes in water. Season with salt and pepper.
Bring to the boil, cook over medium heat for about 25 minutes. Wash the rosemary, shake dry and pluck the needles from the stems. Remove soup from the stove. Finely puree everything with a blender.
Season again with salt, pepper and sugar. Heat the milk and rosemary in a small pot and foam up. Arrange the soup in plates and garnish with milk foam.