For the marinade: In a shallow dish, mix together the onion, rice wine, and ginger. Add the fish and, marinate for 20 minutes, covered, in the refrigerator.
For the sauce: In a small pan, heat the lemon juice, hoisin sauce, soy sauce, and chile flakes and thicken the mixture with the cornstarch and water slurry, if necessary. Set aside. Cook's Note: If your sauce is a little sharp, add a pinch of caster sugar.
For the bread crumbs: Mix the crushed chiles, salt, white pepper together in a bowl. Add in the bread crumbs, then tip them onto a plate or tray. Set aside.
For the coating: Remove the fish from the marinade and dip the strips in the flour, shaking off the excess flour, then in the eggs and, finally, in the seasoned bread crumb mixture. Heat a wok over high heat and fill it to a quarter of its depth with enough groundnut oil. Heat the oil to 350 degrees F. Test the temperature by dropping a cube of bread into the oil and seeing if it in turns golden brown within 15 seconds. Deep fry the coated fillets until they are golden brown. Remove them with a slotted spoon and drain them on an absorbent paper towel. Serve immediately with the sauce and Roasted Sweet Potato Chile Chips, recipe follows.
Preheat an oven to 350 degrees F. Put the olive oil, sea salt, crushed dried chile flakes and black pepper into a roasting tin. Add the sweet potato slices and turn them to coat in the seasoned oil. Roast in the oven for 20 to 30 minutes, depending on the thickness of the chips. Serve immediately.
Ensure your wok is stable before you deep-fry.