Combine the mustard, oil, sesame seeds, cumin and cinnamon.
Roll up the rashers of bacon, thread the bacon, cubes of beef, onions and prunes alternately onto the skewers. Brush the skewers with the marinade, cover and marinate for approx. 30 mins.
Season the skewers., cover and grill over/on a medium heat (approx. 200 °C for approx. 15 mins., turning occasionally.