Begin by rinsing and draining the sauerkraut, especially if you're using canned, to reduce excess saltiness. Place it in a large mixing bowl.

Next, thinly slice the red onion and set aside in a small bowl.

In the mixing bowl with sauerkraut, add the sliced red onion and any optional ingredients. Toss gently to combine.

Taste the mixture and adjust seasoning as needed, adding salt or vinegar carefully.

Transfer the salad to a sealed container and refrigerate for at least one hour. Serve chilled.