Coriander-spiked basil-yogurt dressing classes up simple sliced tomatoes. Use a variety of tomato colors and sizes for most visual impact. You can make the dressing up to a day ahead, but slice and dress the tomatoes as close to serving time as possible.
Toast the coriander seeds in a small dry pan, moving constantly, until fragrant, about 2 minutes. Let cool on the counter or a cutting board. Then crush the seeds with the base of a small pan or a large serving spoon and set aside. Fan the tomatoes on a platter, overlapping as needed. Stir the yogurt, basil, shallot, and salt together, then drizzle over the tomatoes. Season with the coriander and serve immediately.