Thinly slice the cucumbers and radishes using a sharp knife or mandoline.; Chop the fresh mint and dill—don’t skimp, herbs bring the magic!
In a small bowl, whisk together buttermilk, Greek yogurt, lemon juice, garlic, honey, salt, and pepper until smooth.; Taste and adjust seasoning—add a little more salt or honey if needed.
Combine cucumbers, radishes, and herbs in a large bowl.; Pour the dressing over the top and gently toss to coat.; Let it sit in the fridge for at least 15 minutes before serving (this helps the flavors meld).
Transfer to a serving dish and garnish with extra mint and a pinch of flaky sea salt.; Best served chilled, making it a perfect make-ahead side dish for summer cookouts!