Cut cucumbers in half lengthwise and scoop out the seeds. Cut into 3/4 inch chunks. If the chunks aren't firm, place them in a colander and sprinkle with salt. Let drain 20 minutes (if they are firm you may omit this step).
Place butter in a medium to large skillet over medium heat. When it melts, add the onion and cook 5 minutes. Stir in the cucumbers and cook another 5 minutes. Sprinkle with black pepper to taste.
Reduce heat to low and stir in sour cream and plenty of dill. Stir and serve warm.