This pesto is a merger of Italian basil pesto and a miso–sansho leaf sauce, called kinome ae, that we learned in Miyato, Japan. Essentially, umami-rich miso takes the place of cheese, supplying creaminess as well as body. Toasted walnuts add to the richness. Use either white or red miso, or a combination. The former is sweeter and milder, the latter bolder and more savory. We toss the pesto with pasta and especially like spaghetti, but short, sauce-catching shapes like gemelli and fusilli also are good. Or add it to a tomato salad, roasted or grilled eggplant or zucchini, simmered or steamed potatoes, or seared, sautéed or grilled white fish. The pesto can be made up to three days in advance; store it in an airtight container with plastic wrap pressed directly against the surface to protect against oxidation; bring to room temperature before use.