Herb-Stuffed Pot-Roast Guinea Fowl with Garlic and Onion Sauce

• 3 lb / 1.35 kg guinea fowl
• fresh herbs, such as tarragon, chervil, basil, pa

Gently ease the skin away from the breasts and thighs of the guinea fowl, inserting your finger between skin and flesh at the neck end of the bird. Push the herbs under the skin. Peel off thin strips of lemon zest, and put this inside the cavity, together with any extra herbs. Squeeze the lemon and rub the juice over the bird, then season it lightly inside and out. Separate and peel all the gar