Place the salmon fillets in a non-metal bowl. Mix the soy sauce, ketchup, rice vinegar, sugar and garlic together. Turn the salmon in this marinade and marinate for at least 30 minutes.
Then heat 4 tablespoons of oil in a preheated wok and stir-fry the leek rings over medium heat for about 10 minutes. Fish the vegetables out of the pan with a skimmer and distribute them on preheated plates. Add the remaining oil to the wok, add the salmon, marinade and chilli strips to the wok and fry for 4 minutes. Distribute immediately on the leek rings and serve.