Cook pasta according to box directions in a pot of salted, boiling water. Rinse with cold water and set aside to cool fully.
Sautee some the vegetables:
A-Melt butter in a large skillet.
B-Add onion and carrot, sauteeing until onions are translucent and carrots are softened. The garlic, if using dried, should be added to the cooking onion & carrot. If using fresh garlic, add it when the carrots & onions are almost finished cooking.
C-Add the frozen peas and cook just til warm.
D-Set aside the cooked vegetables to cool.
Mix the dressing:
A-In a small bowl, add mayonnaise, vinegar, mustard, salt, pepper, and cayenne. Whisk well to combine and set aside.
Prepare the rest of the raw vegetables:
A-slice celery thinly, rough-chop the olives and parsley, finely chop the red onion.
Combine everything together when fully cooled:
A-drain the tuna and flake at the bottom of a large bowl.
B-add the celery, red onion, chopped olives, parsley, and the cooked vegetables.
C-add the dressing.
D-fold everything together until well mixed, seasoning to taste if necessary.