Lay meat flat and then place in a heavy plastic bag. Measure remaining ingredients in a food processor and process until thoroughly mixed. Pour around meat, squeeze out air and seal. Marinate for 24 hours or longer.
Place meat and marinade in a roasting pan, meaty side up. Place about 20 cm from the heat. Grill for 15 minutes, turn meat and grill 15 minutes longer.
Cut across grain of meat when carving. Alternatively meat can be cooked on the barbecue.
Delicious served cold as well.