Slice 3 medium cucumbers and 1 bunch radishes. Cut into half all the plum or cherry tomatoes (10 yellow, 10 orange, and 10 red). Add the prepared vegetables into a large bowl. Finely chop 1 bunch chives to equal to 1/4 cup and 1 bunch dill to make 1/4 cup. Add prepared fresh herbs to the bowl with salad and gently mix with a spoon.
In a small bowl, combine and stir together, 1/4 cup sour cream, 1/4 cup mayo and ½ tsp kosher salt or to taste. Refrigerate the dressing until ready to serve. Refrigerate dressing-free salad for a day or 2 max until ready to serve. Do not store for prolonged time as the tomatoes will start get watery and radish will change its flavor. Just before serving, stir the salad to coat in dressing. Add more salt to taste if necessary.