Instant Pot Creamy Potato Soup [Dairy-Free, Oil-Free, Gluten-Free, Vegan]

1 large yellow onion, diced
2 stalks of celery, chopped finely
3 cloves of garlic, minced
2 large carrots, chopped into larger bite-sized chunks
3 lbs. of peeled Russet potatoes, peeled and chopped into larger bite-sized chunks
1 1/2 cups unsweetened soy milk or canned coconut milk
1 T Mrs. Dash Garlic and Herb Seasoning or other salt-free seasoning
Salt and black pepper to taste

Steamfry onion and celery in the pressure cooker pot until tender (using SAUTE/BROWN setting), adding a small amount of water if the pieces begin to stick to the bottom. Add in the garlic and steamfry for one more minute. Add the rest of the ingredients, seal the lid, and cook on high pressure for 6 minutes with NATURAL RELEASE. Open the lid, let the soup cool a few minutes, then ladle out HALF of the soup, AVOIDING THE CARROTS, and blend in a high-speed blender until very smooth. Pour the blended soup back into the remaining soup into the pot. Stir well, taste, and add salt and/or pepper if needed. Top with chopped green onion and chopped avocado, if desired.