"Traditional cold rice salad is considered fast food in Italy, used for picnics and lunches on the go. Great for hot days when you don't want to heat up the kitchen. Add a few drops of your favorite hot pepper sauce for a dash of spice if you like. Many Italians add a few tablespoons of mayonnaise at the end."
Combine water, rice, carrot, peas, and salt in a saucepan. Bring to a boil; reduce heat and simmer until rice is tender but still firm to the bite, about 14 minutes. Drain excess water; let cool, 10 to 15 minutes.
Mix prosciutto cotto, Swiss cheese, button mushrooms, corn, green olives, black olives, pickle, artichoke hearts, olive oil, thyme, and oregano together in a large bowl. Stir in cooled rice mixture. Fold tuna into the salad.
Divide salad among 4 serving plates; garnish with hard-boiled eggs. Chill before serving, at least 30 minutes.