- Pre-heat oven to 200 °C / 400 °F / gas 6.
- Weigh the duckling, prick the skin all over with a skewer or sharp fork.
- Place breast-side down on a rack in a roasting tin.
- Roast in the top of the oven, basting occasionally, for 20 minutes per 450g (1 lb).
- Weigh the chicken.
- Place in a shallow roasting tin and roast below the duck on the lowest shelf of the oven for 20 minutes per 450g (1 lb) plus 20 minutes.
- Cool both for 1-2 hours until cool enough to handle.
- Make a slit along each side of the breast bone of both the chicken and the duck.
- Remove and discard the skin.
- Carefully remove all the flesh from the carcasses and cut the flesh of the birds into thin strips about 5 cm (2 inches) long.
- Cook the carrots in boiling water for 8 minutes until just tender.
- Drain and rinse in cold water.
- Cook the potatoes in boiling water for 15 minutes until tender.
- Drain and leave to cool, then dice finely.
- Make the dressing by whisking the oil, lemon juice, mustard and sugar together.
- Choose a large oval platter for making up the salamagundi.
- Place the potato and peas in the bottom of the dish to give a flat base.
- Arrange the carrot strips or a layer of cucumber on top, following the oval shape of the platter.
- Pour over a little dressing.
- Next, arrange a layer of cucumber or carrot, slightly inside the first layer so that it may be easily seen.
- Top with more layers of chicken, peas, tomato slices, celery and duck.
- Make each layer smaller than the previous one so that the lowest layers can all be seen.
- Sprinkle each layer with dressing.
- Continue layering until all the ingredients are used up.
- If using the eggs, shell and halve them, then top each half with a little mayonnaise.
- Garnish with a few radish slices and stuffed olives, arranged around the edge of the dish.