Cut the beef into strips that are approximately 2cm wide and the same length or close to the length of the bacon strip; about 1/2cm thick.
Make the beef and bacon rolls by laying a strip of bacon on a strip of beef and rolling them together so that the beef is on the outside when you finish rolling. Insert a toothpick so that it goes in on the bottom left side and comes out the top right side when looked at vertically.
In large frypan, saute onions and butter until onions are tender. Lay a single layer of beef bacon rolls in the frypan. Brown them on medium heat, turning once or twice. Cover the frypan and simmer about 2 hours.