To make the marinade, mix mayonnaise, vegetable oil, and Dijon mustard.
Cut the turkey fillet into pieces of the size you need and, putting it in the cooked marinade, leave the meat to marinate for 2-3 hours.
Then put the marinated pieces of barbecue on skewers, alternating them with chopped onion rings and sweet pepper.
Fry the skewers in a skillet or grill until cooked. Serve barbecue on the table with fried vegetables, mushrooms and lettuce.