Gyeran bap is what Korean students and hungover adults make when there is nothing in the house. Rice, an egg, soy sauce, sesame oil, and if you are lucky a sheet of seaweed crumbled over the top.
The whole thing is designed to be stirred into a mess before you eat it, so do not worry about how it looks in the bowl. A knob of butter melting into the hot rice is not traditional and is entirely worth it.