Peel and dice sweet potatoes, onion and potatoes. Sweat briefly in the heated oil, fill up the vegetable stock and cook until soft. Then pour off and save the cooking liquid. Add orange juice, puree everything to the desired consistency and stir in the butter. Possibly. Add a little more of the cooking liquid.
Season with sugar, salt, pepper, nutmeg and, if desired, a pinch of cinnamon. Garnish the mashed sweet potatoes with roughly chopped peanuts.