To prepare a vegan potato soup recipe in an instant pot, you will first need to prepare the potatoes. You can use any type of potatoes that you like, including sweet potatoes, yams, and rutabagas. If you don't want to use sweet potato, then you can skip this step. In the Instant Pot, heat the olive oil over medium-high heat. Add the onion and garlic and saute until the onions are translucent, about 5 minutes. Stir in the tomatoes and cook until they are heated through, 2 to 3 minutes more. Remove the vegetables from the heat and add the potato puree. Pour the soup into the pot and close the lid. Cook on high heat for 1 to 2 hours.