2 tablespoons sweet butter or oil
1 medium onion — finely chopped
3 stalks celery — thinly sliced
5 sweet potatoes (about 2 pounds) — peeled and grated
2 large McIntosh apples — peel, core, grate
5 cups chicken stock or bouillon — or
vegetable stock or bouillon 1 1/2 teaspoons grated orange peel
1/2 teaspoon salt — or to taste
serves 6 to 8
Heat the butter in the pressure cooker. Saute the onions until soft, about 3 m inutes. Add the celery and grated potatoes and toss to coat with the butter. Add the grated apples, stock, 1 teaspoon orange zest, and salt. Lock the lid i n place and over high heat bring to high pressure. Adjust the heat to maintain high pressure, and cook for 4 minutes. Let the pressure drop naturally or use a quick-release method. Remove the lid, tilting it away from you to allow any excess steam to escape.
If the soup seems too thin, puree about 1 third of it and stir the puree back i nto the soup. Stir in the remaining 1/2 teaspoon orange zest and salt to taste . Heat thoroughly before serving.