Place the Waxy Potatoes and Carrots in a large pot, cover with cold water, add a generous pinch of Salt, bring to a boil and simmer until both are tender when pierced (about 15–20 minutes). Add the Peas in the last 3–4 minutes of cooking if they are frozen or tenderize them separately and drain.
While the vegetables cook, put the Eggs in a small saucepan, cover with cold water, bring to a boil then reduce to a gentle simmer for 9–10 minutes for hard-boiled eggs; plunge into cold water and peel when cool.
Drain the potatoes, carrots and peas and let them cool enough to handle. Peel the potatoes if you prefer, then dice the potatoes and carrots into uniform small cubes; roughly chop the peas if large.
Drain the Canned Tuna in Olive Oil well and flake it into large flakes with a fork into a large mixing bowl.
Add the diced vegetables and chopped eggs to the bowl with the tuna, then stir in finely chopped Roasted Red Pepper (Piquillo) and sliced Manzanilla Olives.
Fold in Mayonnaise until everything is evenly coated — start with a few tablespoons and add more to reach your preferred creaminess. Taste and adjust seasoning with more salt if needed.
Cover and chill the ensaladilla for at least 1 hour to let the flavors meld. Serve chilled or at room temperature, garnished with reserved sliced egg, extra roasted pepper strips or olives if desired.
