Combine the ground beef, salt, paprika, pepper, egg yolk, cola beverage and flour and mix well.
Chill for about 1 hour.
Saute the onion and the green and red peppers in a small amount of butter in a skillet until soft, then remove and set aside.
Shape the beef mixture into thick patties and cook in the skillet until done and browned.
Top with the onion mixture and serve.