Gary Danko, of San Francisco's Restaurant Gary Danko, gave us this recipe. At the restaurant, he uses king trumpet mushrooms, but we've substituted the more readily available shiitake mushrooms. Danko serves this with herb spaetzle and caramelized cipollini onions. Prep and Cook Time: 1 1/2 hours, plus at least 2 hours to marinate. Notes: The flavor of bison is similar to that of beef but slightly sweeter and cleaner, and the meat is very lean. It can easily be ordered online, and quality butchers or gourmet groceries can order it for you if you give them at least a week's notice. Once you've trimmed the meat, tying the loin together with twine for roasting will ensure that it has a neat shape when you slice it.