Wash the baby cucumbers and radishes, then slice the cucumbers into thin rounds, julienne the red onion, and cut the radishes into thin slices.

In a medium mixing bowl, combine Greek yogurt, mayonnaise (if using), horseradish mustard, honey, lemon juice, minced garlic, and fresh dill. Stir until smooth and creamy, seasoning with salt, pepper, and optional chili flakes.

Add the sliced cucumbers, radishes, red onion, and corn to the bowl. Gently toss until well-coated.

Cover the bowl with plastic wrap or transfer to an airtight container and refrigerate for at least 30 minutes.

After chilling, toss the salad gently again before serving and garnish with additional fresh dill, if desired.