How to Make It
Combine radishes, cucumbers, vinegar, and 1/2 teaspoon of the salt with 1/4 cup water in a medium bowl. Let stand at room temperature at least 15 minutes or up to 1 hour to pickle. Drain radish mixture, reserving pickling liquid for another use (such as vinaigrette).
Heat oil in a small skillet over medium. Add cumin seeds, and cook until golden and fragrant, about 30 seconds. Cool 5 minutes.
Meanwhile, gently stir together drained radish mixture, yogurt, lemon zest and juice, pepper, and remaining 1/2 teaspoon salt in a medium bowl. Top with cooled cumin seeds, and serve immediately with pita chips or grilled naan.