Place a large soup pot or Dutch oven over medium heat. Add butter or oil to pan. Once butter is melted, add the onion. Cook for about 5 minutes, stirring occasionally, until onions are soft. Add the potatoes, stock and 1 teaspoon salt. Bring to a boil. Cover and cook for 15 minutes. Add the corn and cook an additional 15 minutes. Whisk in the flour until completely dissolved. You will notice the juices getting thicker. Remove from heat. Add the milk. Season with salt and pepper to taste.
Instant Pot Directions
Turn the pot to saute and add the oil to the pot. Add the onions and saute, stirring occasionally until they are soft. Add the potatoes, corn, stock and 1 teaspoon salt to the pot. Sealing the lid and close the steam vent. Turn to pressure cook on high (more setting) for 10 minutes. Once it's done cooking, release the steam from the vent. Open the pot and whisk in the flour. Then stir in the milk. Season with salt and pepper to taste.