Cook macaroni according to package directions to "al dente". Drain noodles saving 1-2 cups of the pasta water. Place in a bowl to cool. Toss noodles with peas, cider vinegar and salt and pepper.Allow to cool to room temperature. Toss with some of the pasta water a little at a time if noodles become too dry and sticky while cooling.
In a small bowl, combine mayonnaise and sour cream. Add to cooled noodles. Stir until evenly coated. Add tuna and stir until well combined. Add additional salt and pepper to taste, if needed.
Peel and chop (or slice) hard boiled eggs. Stir into the macaroni salad of place on top for presentation. Garnish with green onion (optional) and serve.