In a shallow-sided pan or tray, warm the oil and add the baby onions, along with the thyme, garlic, star anise and peppercorns to 110°C, then add the salmon supremes and poach for 10 to 12 minutes.
Whilst these are cooking, heat up a saucepan, then pour in the vermouth and fish stock, and reduce by a half. Add the cream and reduce down again to a coating consistency Check seasoning and keep warm.
Remove the salmon from the tray and place on some kitchen paper to drain. Keep warm.
Heat up the sauce and drop in the crayfish and chopped sorrel. Spoon onto warmed plates, with the crayfish at triangular points, and place the salmon in the centre. Peel back half of the salmon skin and garnish with a few of the aromats and some garden herbs. Serve immediately.