1.Combine onion, garlic, thyme sprigs, vinegar, brandy and port in small saucepan; bring to the boil. Reduce heat; simmer, uncovered, about 10 minutes or until reduced by about three-quarters. Strain port mixture into small jug (you will need ¾ cup strained liquid); discard solids. Cool.
2.Meanwhile, discard sinew from livers; pull lobes away from connecting tissue.
3.Preheat oven to 160°C/325°F. Grease thick metal 1.6-litre (6½-cup), 13cm x 23.5cm x 6cm (5-inch x 9-inch x 2.5-inch) loaf pan or glass or china loaf-shaped dish. Line base and sides with baking paper, extending paper over sides.
4.Melt ghee in small saucepan.
5.Blend or process livers, port mixture, oregano and eggs about 3 minutes or until smooth. Gradually add warm ghee in a thin, steady stream; blend until combined, season. Strain mixture through a very fine sieve into a large jug, pressing down on solids; discard solids.
6.Pour liver mixture into pan, place pan in tea towel-lined large baking dish; pour in enough boiling water to come halfway up sides of pan.
7.Cook parfait, in oven, about 20 minutes or until top is firm and temperature of parfait is 70°C/160°F. Remove parfait from baking dish; stand 1 hour.
8.Melt extra ghee in small saucepan; stir in thyme leaves. Pour mixture over parfait. Cover; refrigerate.
9.Make sourdough wafers. Preheat oven to 200°C/400°F. Melt ghee in small saucepan. Slice bread thinly on an angle. Brush one side of bread with ghee; place on oven trays, sprinkle with salt. Bake about 3 minutes or until browned lightly and crisp.
10.To unmould parfait, rub sides of pan with a hot cloth; run a hot knife around sides of parfait. Invert parfait onto board, remove lining paper. Cut parfait into thick slices. Serve with sourdough wafers, cornichons and watercress.
It is best if the sourdough baguettes are a day old before slicing for this recipe. Sourdough wafers can be stored in airtight container for up to 3 days.Note