Best Macaroni Salad Ever

"The most important things are to not rinse the macaroni, and to let it cool before adding the dressing. If you add it while the pasta is too hot, the mayo sort of melts, and you get a greasy salad. By letting it cool, while tossing, the macaroni gets nice and tacky, and will grab the sauce a lot better." ~Recipe Link

Ingredients for 12 portions:
1 pound (4 cups) uncooked elbow macaroni, cooked in well-salted water

For the dressing:
1 cup mayonnaise, plus an extra spoon as needed
1/4 cup white vinegar
1 or 2 tbsp white sugar
2 tablespoons Dijon mustard
2 tsp kosher salt, plus more to taste
1/2 teaspoon ground black pepper
1/8 tsp cayenne
1/2 cup green onions, white and light parts
1 cup finely diced celery
3/4 cup diced red bell pepper
1/2 cup diced green pepper (I used poblano and jalapeno)
1/2 cup grated carrot