Slice the cucumbers and onion and spread onto a baking tray or large flat surface. Sprinkle the salt and pepper all over the cucumbers and let them sit for 15 minutes.
Combine the sugar and vinegar in a saucepot and bring to a boil. Once dissolved turn the heat off and add 1 cup of cold water to the pot. Let the mixture cool down.
Place the cucumbers into a flat baking dish and pour over the vinegar mixture and mix in the dill. Cover and refrigerate for at least 2 hours but preferably overnight. At the halfway point, mix the cucumber salad and return to the fridge. Enjoy!
