Clean and wash the leek, cut in half lengthways and cut into fine strips. Core the apple, do not peel it, divide into 6 wedges and cut into leaves. Steam the leek strips in a little oil with salt and pepper for approx. 3 minutes and set aside.
Dry off the fish fillets, season with salt and pepper, flour and fry in a pan with a little oil. While frying, add the apple slices to the leek and season with a little sugar and vinegar.
You can of course also use other fish e.g., Take cod, salmon, sea bass.