Old Fashioned but still fabulous.
Cook Macaroni al dente in salted water according to package directions. Rinse immediately in cool water and drain well. Add to a large bowl.
Add celery, onion, pepper, green onion, and hard-cooked eggs. Toss together. Add in tuna if using and gently toss.
Mix Dressing ingredients: mayonnaise (or mayo/yogurt mixture), vinegar, pickle relish, if using, mustard powder, sugar, salt, and pepper. Combine gently with the macaroni mixture. Refrigerate.
Best if refrigerated for about an hour before serving. If mixture becomes too dense, add a little extra mayonnaise or a tablespoon or two of water to loosen the consistency.