Bring a large pot of salted water to a boil. Cook 8 oz macaroni until just tender, about 8 minutes. Drain, rinse under cold water until cool, and drain well.

In a large bowl, whisk together 1/2 cup vegan mayo, 1 tbsp mustard, 1 tbsp apple cider vinegar, 1 tsp sugar, 2 tbsp relish, 1/2 tsp salt, and 1/4 tsp pepper until smooth.

Dice the celery, bell pepper, and red onion into small, even pieces. If using dill, chop 2 tbsp.

Add the cooled pasta and diced vegetables to the dressing. Fold until evenly coated. Taste and adjust seasoning. Serve right away or chill. Finish with fresh dill before serving.