Add the Good Stuff: Once the potatoes are slightly cooled, add the celery, onion, relish, vegan mayo, mustard, salt, and pepper. If you're going for that classic eggy vibe, mix in a pinch of black salt too.
2 cups celery, ½ cup white onion, ½ cup sweet pickle relish, ½ cup vegan mayonnaise, 1 ½ tablespoons yellow mustard, ¼ teaspoon black pepper, Optional: Pinch of black salt, ¾ teaspoon sea salt