Slice the cucumbers and radishes thinly, using a sharp knife or a mandoline if you have one.
Transfer the sliced cucumbers and radishes to a large bowl, then mix in the dill and chives until evenly combined.
In a separate bowl or measuring cup, whisk together the Greek yogurt, olive oil, vinegar, honey, kosher salt, garlic powder, and black pepper until smooth.
Pour the prepared dressing over the vegetables and gently toss everything together to coat the salad well.
Since cucumbers release moisture once dressed, it’s best to enjoy the salad immediately for the freshest taste.
To prepare in advance, store the sliced vegetables and dressing separately in the fridge for up to one day, then combine right before serving.