This is one of my favorite soups, with its deeply satisfying, umami flavors and warmth. This Hot and Sour Soup is a wonderful plant-based tonic for those chilly winter evenings. Ingredients are available from your local Asian grocers or online. If you have access to an H-Mart supermarket, you'll find fresh lily buds, tree ears, a variety of fresh shiitakes, and varieties of tofu to choose among.