Bring a large pot of lightly salted water to a boil. Cook pasta at a boil, stirring occasionally, until cooked through yet firm to the bite, about 12 minutes. Drain and rinse several times with cold water until pasta is cool.

Stir pasta, cucumber, onion, and dill in a salad bowl.

Whisk vinegar, sugar, water, vegetable oil, mustard, salt, and black pepper in a separate bowl until sugar and salt have dissolved. Pour dressing over pasta mixture and toss lightly to coat with dressing. Let chill for 2 hours before serving.