Bring a large pot of salted water to a boil and add the dry macaroni. Cook until just firm (al dente), about 8-10 minutes—avoid overcooking since the pasta will continue to soften as it sits in the dressing. Drain the pasta in a colander, then rinse briefly with cool water for about 30 seconds to stop the cooking process and remove excess starch. Spread the cooled pasta on a sheet pan or large plate to cool completely while you prepare the remaining components.

While the pasta cools, prepare all vegetables for the salad. Peel and dice the cucumbers into 1/2-inch cubes, finely dice the green bell pepper, slice the celery stalks into 1/4-inch crescents, and finely dice the red onion. I find it helpful to prep vegetables into separate small bowls so they're easy to add all at once—this keeps the assembly quick and organized.

In a medium bowl, whisk together the mayo, sugar, apple cider vinegar, garlic powder, lemon juice, salt, black pepper, celery seed, and Dijon mustard until smooth and well combined. The vinegar and mayo might look slightly separated at first, but whisking thoroughly will create an emulsified, creamy dressing. I like to taste the dressing before adding it to the salad—this way you can adjust the sweetness or acidity to your preference if needed.

In a large mixing bowl, combine the cooled pasta from Step 1, the coleslaw mix, and all the prepared vegetables from Step 2. Pour the coleslaw dressing from Step 3 over the salad and stir gently but thoroughly with a large spoon or spatula, making sure the dressing coats all the pasta and vegetables evenly. Don't be timid with mixing—you want every component to get dressed.

Cover the salad and refrigerate for at least 30-60 minutes before serving. This resting time allows the flavors to meld and the pasta to absorb some of the dressing, creating a more cohesive dish. The salad will keep well in the refrigerator for up to 3 days, making it an excellent make-ahead option for gatherings.