Ribbon Vegetable Salad

1 medium English cucumber
2 large carrots
2 large celery ribs
2 scallions
2 tsp. seasoned rice vinegar, or to taste
1/8 tsp. Asian sesame oil

Halve cucumber lengthwise and seed. Peel and trim carrots. With a vegetable peeler cut cucumber and carrots lengthwise into thin ribbons, transferring to a bowl. Cut celery and scallions crosswise into 3-inch-long pieces. Cut pieces lengthwise into julienne strips, transferring to bowl. Add vinegar and oil and toss to combine well.