Peel the garlic and rub over the lamb steaks. Using your hands, rub the olive oil over the lamb.
Season the lamb with black pepper. Remember to thoroughly wash your hands after handling raw meat.
Heat the grill pan and cook the lamb for 3-4 minutes on each side. Remove the lamb from the grill pan and wrap in tin foil to rest for 5 minutes.
Peel the onion and finely slice. Remove the top of the chilli, cut in half lengthways, deseed and slice finely.
Finely chop the mint and coriander.
Peel and remove the stone from the mango and finely slice.
Place the watercress in a mixing bowl and add the onion, mango, chilli and herbs.
Zest and juice the lime and pour into a small bowl. Add the olive oil and stir.
Pour the dressing over the salad and mix.
Remove the lamb steaks from the tin foil and slice. Serve the lamb on top of the salad.