Combine the dressing ingredients first.
Add the chopped veggies to the dressing so that they can flavor each other, and put into the fridge to blend (at least 4 hours, but overnight would be great). You can also add the optional ingredients at this point.
Cook the macaroni in 4 quarts of salted water until done, drain but do not rinse! Allow to cool completely before adding the dressing. Stir the macaroni occasionally to help it cool.
When the pasta is cool and tacky, add the dressing to it and stir through. Put back into the fridge overnight, or for at least 4 hours.
Remove the salad from the fridge before serving, and taste it; adjust seasonings as needed.
You can freshen the salad up with a dollop of mayo and 1-2 tsp of cold water.
Garnish with some chives or parsley.
This can be kept in the refrigerator for another 2-3 days. If it gets too thick, you can loosen it with a little water stirred in.