Have the butcher butterfly the leg of lamb, or do it yourself.
Combine all remaining ingredients in a glass, enamel, stainless, or plastic container and beat with a whisk or fork until combined. It takes a few minutes.
Add the lamb, turning it to make sure it is coated on all sides. Marinate two hours at room temperature, or overnight in the refrigerator. Check occasionally to make sure that it is still coated with the marinade.
Prepare your braai and cook the lamb – about 20 cm above the coals – for 15 minutes on each side. Brush occasionally with the marinade. Set aside to rest for 20 minutes.
Cook the rice according to the instructions on the pack.
Carve the lamb and serve with rice, heated marinade and a sprinkling of fresh herbs.