Thick, quick-cooking udon—Japanese wheat noodles—make easy work of supper. We infuse ours with robust flavor with a peanut-sesame sauce seasoned with ginger, soy sauce and miso. Traditionally, this dish calls for Chinese sesame paste, which has a dark color and rich flavor, but can be difficult to find. Instead, we use natural peanut butter which turned out to be a fine substitute. The sauce can be made ahead and refrigerated for up to a week; bring it to room temperature before using. Check the packaging of your noodles for their cooking timing. To round out the dish, add cooked shredded chicken, poached shrimp, cubes of sauteed tofu or edamame.