Using a vegetable peeler, peel the cucumber lengthwise into long, thin ribbons. Repeat with carrot. In a large bowl combine cucumber and carrot ribbons, onion, dill weed, and pepper. Set aside.
In a small saucepan combine vinegar, sugar, and salt; bring just to boiling over medium-high heat. Pour immediately over vegetables, stirring to combine; cool. Cover and chill for 1 hour or up to 3 days.