Heat up a skillet over medium high heat. Once heated, add the cooking oil and the tuna. Stir quickly.
Add the vegetables and the spicy tuna sauce and mix them well so that everything is coated with the sauce. (If you make the spicy tuna sauce from option 2 to serve over rice or pasta, only add half of the sauce and use the remainder later - over rice / pasta.) Add the sesame seeds. Remove from the heat. Serve with rice or spaghetti.