serves 6 to 8 *use apples such as McIntosh; peel, core, and cut into eighths Heat the butter in the pressure cooker. Saute the onion, stirring frequently, until golden brown, about 4 to 5 minutes. Add the celery and split peas, stirr ing to coat well with the fat. Add the 4 cups of water plus 2 cups stock, maki ng sure to scrape up any bits of onion that are stuck to the bottom of the pot. Add the sweet potatoes, apples, bay leaf, and mint. Lock the lid in place an d over high heat bring to high pressure. Adjust heat to maintain high pressure and cook for 10 minutes. Let the pressure drop naturally, about 20 minutes. Remove the lid, tilting it away from you to allow any excess steam to escape. Stir well to blend the ingredients and thin with additional stock, if desired. Remove the bay leaf and add salt to taste before serving.
Note: By coating the peas with oil or butter and never filling pressure cooker about the halfway point, split peas can be safely cooked in a pressure cooker.
Note: This soup is very thick and can be served as is or thinned with a few cu ps of vegetable stock.
Note: Two teaspoons of dried mint give the soup a "hint of Mint'; three teaspo ons strongly flavor it.