Add macaroni (and potatoes if using), vinegar, water and salt to pressure cooker cooking pot.
Lock on lid and close pressure valve. Cook at high pressure (most pressure cookers default to high pressure) for 2 minutes.
When beep sounds, wait 5 minutes and then quickly release the rest of the pressure by toggling the pressure valve back and forth, so that you don't spew liquid everywhere.
Remove the lid, turn off the pressure cooker and give the macaroni a good mix. There should be a little liquid left in the pot, which will absorb into the macaroni.
Stir in carrots and mix until combined evenly throughout the macaroni.
Whisk together mayonnaise, milk, sugar and pepper, until smooth.
Mix in smashed egg (if using) and combine well.
Pour dressing over macaroni and mix through.
Pour macaroni to a container and place in the refrigerator until it is chilled.
Since making this video, the recipe has been slightly changed. The addition of the pepper, potato and egg make this Hawaiian Macaroni Salad even better.If you prefer a less tangy taste, use less vinegar. I like to add the vinegar to the cooking water, so that it absorbs into the pasta. If you are concerned about the amount of vinegar in this recipe, try starting with less and then add more in bit by bit once you have mixed in the dressing. Some people prefer more vinegar, some less. I like this recipe as written.Adding the dressing to the hot macaroni makes it easier to mix through and allows the dressing to nicely adhere and absorb into to the pasta.Duke's Mayonnaise and Hellmann's / Best Foods Mayonnaise give the richest and smoothest taste and as the dressing is key to this recipe, I suggest using one of those brands.Brown or white sugar can be used.Whole milk works best, but low fat and no fat can be used to save fat calories.If the dressing is too thick, add a splash of milk or water to thin out the dressing. If you like a more tangy taste, add a splash of red wine vinegar.