Boil the carrots and potatoes (the potatoes with the skins), then clean them and dice them. Add the diced vegetables, the peas, the slice of mortadella also diced, the hard-boiled eggs, thecucumber in salt (if necessary, a fresh cucumber can also be used). Now prepare the mayonnaise for the Russian salad: beat the eggs with the oil (vegetable oil is preferable to olive oil), then add the lemon juice (if you want you can add a teaspoon of mustard). Once it is well blended and creamy, pour it over the vegetables in a salad bowl. Then mix everything well so that the mayonnaise coats all the vegetables and the mortadella. Lastly, add the sour cream (always prepared with fresh cream and lemon juice) and serve the Russian salad as a side dish, decorated with pickled cucumbers.