Remove the legs from the quails. Season well with the salt and herb mix, leave for 1hour. Brush off the herbs and salt, place in an oven proof container cover with olive oil and cover. Place in an oven at 120°C for 1 hour. Drain well and when warm remove the meat and roughly chop. Keep the bones.
For the cabbage:
Dice the onion and keep the trimmings for the sauce. Remove the outer leaves of the cabbage, then remove 4 whole leaves, the rest of the cabbage can be sliced and remove the veins.
Cook the leaves in boiling salted water and refresh in iced water, drain on kitchen cloth. Sweat the diced onion in olive oil add the sliced cabbage and cook, you may need to add a drop of water.
Next add the chopped leg meat and couscous, check seasoning and allow to cool. Using a cloth fill each cabbage leaf with the mixture and shape into a ball, these can be heated through in a moderate oven.
For the sauce:
Seal the quail and roast in the oven at 200°C for 5mins approx, allow to rest for a further 5mins. Remove the breasts and reserve.
Chop the carcase and leg bones; fry lightly with the onion trimmings add the Madeira and enough chicken stock or water to just cover the bones.
Bring to the boil and simmer for 10mins, pass through a fine strainer. Next reduce with a knob of butter until it reaches coating consistency.
To plate, warm the mango in the sauce. Cut the breasts in two, arrange the mango and breast meat around the cabbage ball and coat with the sauce.