serves 6 Here are all the colors of a brilliant autumn day. Since sweet potatoes cook m ore quickly than beets, cut them into thicker slices, which are more likely to keep their shape. The beet greens add a very appealing spinach-like flavor. T he pressure cooker tenderized beet skins so much that removing them becomes mor e a matter of aesthetics than necessity.
Cut the beets from their greens and peel or scrub them. Cut the beets into 1/4 -inch slices and cut the slices in half. Set aside.
Cut and discard the red stems from the beet greens. Rinse the beet green in a sinkful of cold water, taking care to remove all of the sand. Discard any blem ished or very large, tough leaves. Drain and chop the beet greens into strips about 2 inches wide. Use about 4 cups of tightly packed chopped greens for the soup, saving the remainder for stock or another use. (They're delicious when s auteed in olive oil with lots of garlic). Cut the peeled sweet potatoes into 1/2-inch slices and cut the slices in half. Set aside. Heat the butter in the cooker. Add 2 teaspoons of the ginger and the onions an d cook until the onions are soft, about 3 minutes. add the beet greens, sliced beets, sweet potatoes, and stock. Lock the lid in place and over high heat bring to high pressure. adjust the he at to maintain high pressure, and cook for 7 minutes. Reduce the pressure with a quick-release method. Remove the lid, tilting it away from you to allow any excess steam to escape. Stir in the remaining 1/4 teaspoon ginger and the ora nge zest. Add salt to taste and serve immediately.