To make this silky soup, we simmer carrots in carrot juice, resulting in an especially vibrant and full-flavored puree. The addition of baking soda may seem unusual, but it helps break down and tenderize the carrots so they blend into a smooth, velvety texture. Fennel seeds and cumin add earthiness and spice to balance the carrots’ natural sweetness, while a little lime juice added at the end brightens the flavors. Butter-toasted sliced almonds sprinkled onto individual bowlfuls add crunchy contrast.