In a medium bowl, combine yogurt, vinegar, sugar, dill and salt and pepper. Taste and adjust dressings flavors and seasonings as desired.
Place the slicing/shredding disk on slicing side and attach to food processor bowl. Cut onion to fit into food chute and press onion down with food pusher. Cut cucumber to fit into food chute and press down with food pusher.
Place cucumber and onion in a sieve placed over a bowl. Let sit for 15 minutes to give off excess water. Blot cucumber and onions with paper towel and toss with dressing.