Slice the radishes and cucumbers as thin as possible using a sharp knife or mandolin.
Combine the sliced cucumbers, radishes, dill, and chives in a large mixing bowl and stir gently.
In a different bowl, whisk together the Greek yogurt, olive oil, vinegar, honey, salt, garlic powder, and black pepper until smooth.
Drizzle the yogurt dressing over the veggies, then toss everything together so the salad is fully coated.
Serve immediately to enjoy the freshest crunch, or refrigerate the veggies and dressing separately for up to a day and mix before serving.