Cut the turkey breast into small pieces.
Put the pieces in a casserole with 1/4 cup (3 tablespoons) of water.
Add salt and pepper to taste.
Cover and microwave on HIGH for 5 minutes.
Leave to stand for 5 minutes.
Filter the mixture through a strainer (sieve) held over a ter-rine dish, then pour the liquid obtained into a measuring cup and add the gelatin (gelatine).
Stir and microwave on MEDIUM for 2 minutes.
Stir again and add enough water to make up to 1 cup (250 ml/8 fl oz) of liquid.
Add a dash of Tabasco sauce.
Pour half the gelatin (gelatine) mixture into a 1 1/2 quart (1.5 litre/2 3/4 pint) terrine and chill in the refrigerator for 20 minutes until firm.
Peel, halve and stone the avocado pears.
Puree the turkey breast in a food processor with the avoca does, lemon juice, prune brandy or cognac and the remaining aspic jelly.
Taste and adjust seasoning: the terrine should be highly seasoned.
Rinse the sprig of tarragon and pat dry on kitchen paper.
Carefully remove the leaves.
When the aspic in the base of the terrine is firm, arrange the tarragon leaves on top in a decorative pattern.
Spoon the turkey mousse carefully on top, smoothing from time to time to eliminate air bubbles.
Cover with saran wrap (cling film) and chill in the refrigerator for 12 hours.