Dressing - whisk together the seasoning, mustard, vinegar and oils in a small bowl. Set aside. For the salad: Fry the bacon, stirring for 5 minutes. Add the walnuts and cook for 2-3 minutes until crisp. Drain and set aside. Heat the oil in a wiped-out pan, add the shallots and cook, stirring all the time, for 5 minutes. Add garnish and mushrooms and fry for 1-2 minutes. Add the brandy and reduce for 1-2 minutes, or until syrupy. Add the prawns and stir fry over a high heat for 2 minutes or until pink. Add bacon. Toss the salad leaves and arrange on plates. Add remaining dressing to prawn mixture and spoon on top of the salad. Garnish with chives.