Mix the powder of roasted liquorice roots with the liquorice powder in a bowl.
Preheat the oven to 220°C.
Fry the duck skin-side down in a hot ovenproof pan for 5 minutes until crisp.
Drain the fat, turn the duck, and roast in the oven for 10 minutes.
Roll the roasted duck in the liquorice powder mixture and rest in a warm place.
Simmer tamarind fruit with lime juice and water for 15 minutes until soft.
Drain, sieve to remove stones, and blend the tamarind until smooth.
Melt black liquorice with a little water in a pan over low heat.
Blend the melted liquorice until smooth and pass through a sieve.
Blanch the green beans in salted water for 3 minutes then refresh in iced water.
Heat chopped rocket and chicken stock in a pan, then stir in butter, remaining rocket, and beans.
Carve the duck and insert trimmed liquorice sticks into each piece.
Serve duck on liquorice purée with a line of beans and a drizzle of tamarind purée.