Place cucumbers and bell peppers into a colander and allow liquid to drain for 4 hours. While vegetables are draining, place yogurt into a separate colander lined with paper towels and let stand for 4 hours to allow excess whey to drain from the yogurt.
Combine cucumbers, bell peppers, thickened yogurt, sour cream, vinegar, dill, salt, and black pepper in a large salad bowl; chill before serving.
