This colorful side dish features an unusual combination of flavors; the inspiration comes from a recipe in “365,” a cookbook by German food blogger Meike Peters. Earthy sweet potatoes pair well with the subtle citrusy notes of coriander and the fruitiness of orange juice, while savory onion, spicy cayenne and salty olives balance the natural sugars. We love the texture and flavor pop of lightly crushed coriander seeds; a mortar and pestle are the best tools for the task but the bottom of a heavy skillet works, too. If you prefer, you can use 1 tablespoon ground coriander in place of the seeds, but it will require less than a minute to bloom in the oil.