2 tablespoons whole-grain mustard, or more to taste
2 tablespoons cider vinegar or white wine vinegar, or more to taste
Salt and pepper
1 small red onion, halved and thinly sliced
2cups cooked wheat berries
Instructions
Trim the cabbage and grate it by hand or in a food processor. You should have about 4 cups.
Whisk the oil, mustard, and vinegar together in a large bowl. Add a little salt (mustard can be quite salty, so go easy) and a lot of pepper. Separate the onion slices into the dressing and stir until coated.
Add the cabbage and wheat berries to the mixture and toss well. Taste and adjust the seasoning, adding more oil, mustard, or vinegar. Serve right away or cover and refrigerate for up to a day.