Begin by making the stuffing, which is easiest done in a processor. Put all the ingredients except the eggs in the processor and whizz until fairly smooth. Keep the motor running and break in the eggs one at a time to make a fairly sloppy puree. Thread your needle and sew up the wishbone end of the chicken tightly so that none of the stuffing can seep out. Prop the chicken firmly, open end upwards, in a small saucepan or bowl so that you can stuff it. With your fingers and a spoon, gently ease the skin away from the flesh on the breast, and spoon about one quarter of the stuffing under the skin, smoothing it down so that it protects the meat. Fill the cavity with the rest. Wash your hands and put a new piece of thread in the needle. Sew up the skin and hole really carefully and tightly. Remember that the stuffing is runny and you dont want it to leak out into the water, nor do you want any more liquid oozing in to dilute it before it is set. Truss the chicken tightly with string so that it doesnt fall apart in the pan. If you have time, leave the chicken overnight, loosely covered, in the refrigerator. When you are ready to cook, take a huge pan, big enough to hold the chicken, vegetables and bones with plenty of room to spare. Half fill with water, cover and bring to the boil - allow plenty of time. Now add all the broth ingredients except the passata, bring back to the boil and slip in the chicken. There should be enough water to cover everything by several inches. If necessary, add more boiling water. Skim off all the scum that rises to the surface. Simmer for 2 hours, then add the passata. Continue simmering for a further 1-2 hours, topping up with more boiling water as needed. When you are about 30 minutes or so away from sitting down to eat, its back to work. Hoick the chicken out carefully, cover and keep warm in the oven. Ladle about 1.75l of the cooking broth into a clean pan, bring to the boil and add the tapioca or vermicelli. Bring back to the boil, simmer for 5 minutes, then cover tightly and turn off the heat. Go back to the chicken, dismember it and arrange pieces on a serving plate together with slices of the stuffing. Spoon over a little broth to keep it all moist, cover with foil and keep warm in the oven. Taste and adjust the seasoning in the soup and serve, then follow with chicken, stuffing, vegetables from the broth if using, and freshly cooked vegetables.