Thinly slice the cucumbers and radishes into uniform pieces and set them aside. This ensures an even texture and better absorption of flavors.
In a separate bowl, whisk together the sour cream, lemon juice, freshly chopped dill, salt, and black pepper until the dressing is smooth and well combined.
In a large mixing bowl, combine the sliced cucumbers, radishes, and chopped spring onions. Drizzle the prepared dressing over the vegetables and toss gently until everything is evenly coated.
Serve immediately for a crisp, refreshing salad, or let it sit for a few minutes to allow the flavors to meld.