Turn the multicooker to sauté mode, add the olive oil and sauté the yellow onions for 2-3 minutes or until they are soft and translucent.
Add the potatoes, garlic, and vegetable stock. Turn off the sauté mode and place the lid on the multicooker. Set for manual, high pressure with the timer set to 12 minutes. Once the timer goes off allow for a natural release of the pressure. Once the pin drops, carefully remove the lid.
Transfer the contents to a blender or just use an immersion blender inside the multicooker to puree the soup. Once the soup is silky smooth. Stir in the fresh lemon juice, green onions, dill if desired, and adjust the seasoning with the salt and pepper.
(To Prepare on the Stovetop): Place a heavy bottomed pot over medium high heat and add the olive oil. Add the onions to the pot and cook for 2-3 minutes or until they are soft and translucent. Add the potatoes, garlic and vegetable stock and turn the heat to high and allow it to come to a boil then reduce the heat to a simmer. Simmer the soup until the potatoes are very tender about 45 minutes. Transfer the contents of the pot to a blender/food processor or you can use an immersion blender right in the pot. Puree the soup until it is smooth then return to the pot and stir in the lemon juice, green onions, and dill. Feel free to adjust the seasoning with the salt and pepper.