Wash the fillets and dab dry. Mix sesame oil and Cajun. Spread the fillets with it and marinate in the refrigerator for at least 4 hours.
Preheat oven (electric cooker: 80 °C/circulating air: not suitable/gas: see manufacturer). Roast the fillets in the oven for approx. 1 hour.
Meanwhile, for the salad dressing, peel onions, dice finely and blanch briefly. Then drain. Mix vinegar and soy sauce, stir in onions. Season to taste with salt and sugar.
Clean, wash and cut Pak Choi into strips. Heat 2 tablespoons of oil. Fry the Pak Choi in this oil for 3-4 minutes. With sushi mix (for the sushi mix, heat rice vinegar, sugar and salt in a pot until the sugar has dissolved.
Sushi mix keeps for 2-3 months in the refrigerator). Cut the fillets open, arrange on the Asian salad and drizzle everything with salad dressing. Pluck off the coriander leaves and sprinkle over it.