Two-Potato Soup - cooking recipe

Ingredients

1 tablespoon vegetable oil
1 small yellow onion, chopped
2 garlic cloves, minced
2 stalks celery, chopped
1 1/2 lbs russet potatoes, peeled and sliced
3/4 lb sweet potato, peeled and sliced
3 1/3 cups chicken stock or 3 1/3 cups chicken broth
1/2 teaspoon dried thyme
3/4 teaspoon salt
1/8 teaspoon white pepper
1 cup buttermilk or 1 cup milk
1 granny smith apple, unpeeled, cored, and chopped (for topping)

Preparation

In a big soup pot over med heat, let the oil get warmed.
Add in onion, garlic, and celery; stir/saute for 5 minutes or until tender.
Add in potatoes; stir to mix well.
Add in stock, thyme, salt, and pepper; bring to a boil.
Lower heat to med-low and simmer, covered, 15 minutes or until potatoes are soft.
Transfer mixture to a blender or food processor in batches; process until smooth (may use a stick blender). Return soup to pot and add buttermilk.
Simmer 10 minutes or until heated through.
Ladle into individual soup bowls; top with chopped apples.