Place the cubed meat in a bowl, season with a little red wine vinegar and allow to marinate for 10 minutes then rise-off the vinegar.
Return the meat to the bowl and add the crumbled beef bouillon cubes and black pepper, mix to incorporate thoroughly and allow to marinate for at least 20 minutes.
Meanwhile, mix the peanut butter with the oil and stir to loosen. Add this sauce to the meat and leave to marinate for at last 30 minutes.
When ready shake off the excess from the meat and thread onto skewers, alternating each piece of meat with two large cubes of onion. When done, brush the meat and onion with any remaining marinade and cook on a barbecue (or under the grill) for about 20 minutes, turning the kebabs and brushing with fresh marinade every 5 minutes, or so until the meat is done.