• Step 1: Cook the elbow macaroni according to package instructions. Drain and rinse with cold water to cool completely.
• Step 2: In a large bowl, combine the cooked and cooled macaroni, drained tuna, diced celery, and diced onion.
• Step 3: In a separate bowl, whisk together the mayonnaise, sour cream, Dijon mustard, white vinegar, salt, and black pepper.
• Step 4: Pour the dressing over the macaroni and tuna mixture and stir gently to combine. Taste and adjust seasonings as needed.
• Step 5: Cover and refrigerate the tuna macaroni salad for at least 30 minutes to allow the flavors to meld.