Each forkful of this easy make-ahead slaw offers a colorful tangle of zucchini, carrots, bell pepper, onion, and basil.
In a large bowl, whisk together vinegar, oil, celery seeds, sugar, 2 teaspoons salt, and 1/4 teaspoon pepper. Add squash, carrots, bell pepper, onion, and basil. Toss to combine and evenly coat in vinaigrette. Let stand at room temperature 30 minutes and toss again before serving, or cover and refrigerate up to 1 day. Remove from refrigerator 30 minutes before serving.
If using spiralized squash, cut the spirals into 6-inch lengths for easier eating.