Ingredients

· 1 yellow onion, chopped

· 2 celery stalks, chopped

· 3½ cups chicken stock

· 3 cups mashed potatoes

· ¼ cup whole milk

· ½ teaspoon kosher salt

· ¼ teaspoon black pepper

· Unsalted butter and soy sauce

· Chopped celery leaves

Method

Combine the onion, celery, and 2½ cups chicken stock in a small Dutch oven. Bring to a boil over medium-high. Reduce the heat to medium-low, and simmer, stirring occasionally, until vegetables are tender. Add leftover mashed potatoes to the chicken stock mixture, and whisk until well combined. Stir in milk, for a creamier texture. Stir in remaining one cup chicken stock, a little at a time, to thin soup to desired consistency. Cook over medium-low, stirring occasionally, until warm. Season with salt and pepper. Top servings with butter and drizzle with soy sauce. Garnish with chopped celery leaves.