Add vinegar, sugar, salt, celery salt, and black pepper to large mason jar. Shake to combine.

Use a mandolin to thinly slice the red onion, cabbage, and red bell pepper. Use the second thinnest setting. Be very careful.

Grate the carrots. In a large bowl, mix together the onion, carrot, cabbage, and red pepper. Add the mixture to the mason jar with the dressing. Shake to coat. Refrigerate for at least forty minutes and up to an entire overnight. Jar will be ready for picnic; just remember to pack forks and tongs for serving.