Boil the cubed potatoes with sea salt until done but not falling apart. Drain well and set aside to cool off. Cook the peas in a small pan with some water until slightly tender. Drain and set aside.
Chop 3 of the hard-boiled eggs into small cubes. Slice the remaining egg and set it aside (used for garnishing)
Add the cooled diced potatoes to the bowl and mix well. Add more mayonnaise as you go along until you have a soft consistency salad. Taste to adjust the flavor.
Let the Insalata rest in the refrigerator for at least 1 hour, decorate with the sliced egg, and serve.