While preparing Rotini pasta according to package directions, place frozen peas in a colander and rinse well with cool water, removing any ice particles.
Place cooked pasta and peas, ham, onion and bell pepper in large mixing bowl; stir well to combine.
Add 1 cup of mayonnaise to the mixture along with the oil; stir well. Add more mayonnaise as needed, being careful not to add too much or pasta will become soggy.
Add salt and pepper to mixture and stir well.
Cover container and refrigerate at least 3 hours, or overnight, before serving.
This is a great way to use up that leftover spiral ham from family dinners! Try adding in shredded carrots, olives or sweet pickles for a different taste!