METHOD

1. Cut the beef and lamb in to 25mm/l inch cubes. Cut the kidneys in half, skin them, remove the cores and cut each half into 4 pieces. Place the pieces of meat in a large shallow dish. Mix together the olive oil, lemon juice, finely chopped garlic and herbs and pour over the meat. Leave in a cool place for 1 hour to marinate, turning the meat occasionally.
 
2. Heat the grill to medium-high. Meanwhile, remove the rack from the grill pan and line the pan with foil. Thread the pieces of meat on to 4 greased metal
skewers, with the mushroom caps and parboiled onions in between.
 
3. Lay the skewers across the prepared grill pan. Grill about 7. 5cm/3 in from the heat, basting with the marinade and turning meat from time to time, for about 20 minutes or until the meat is cooked.