Slice cucumber and radishes thinly, use mandolin if available, chop the egg but not too small and combine in a salad bowl.
Prepare the dressing by combining all ingredients in a mason jar, put a lid on and shake vigorously until the mixture is smooth. You might want to add more water to desired consistency.
Add 2-4 tbsp of the creamy dill dressing to the salad bowl and toss gently. Add salt and pepper to taste.
Reserve the rest of the creamy dill dressing for other salads.