For the pork, place the gluten free flour, a few pinches of ground white pepper and the dried chilies into a food processor and pulse until mixed. Transfer to a shallow bowl and set aside.
Place the pork steaks in between two sheets of cling film and, using a meat mallet or rolling pin, bash the pork steaks until halved in thickness. Roll the steaks in the gluten free flour mixture until well-coated, then pat lightly to secure the mixture to the meat, shaking off any excess.
Heat a wok until smoking and add the groundnut oil, then add the pork steaks and cook for 2-3 minutes on both sides, or until golden-brown and cooked through. Remove the steaks from the wok transfer to a warm plate to rest. For the sweet and sour sauce, place all of the sauce ingredients into a food processor and blend to a smooth paste.
Pour the sweet and sour sauce into the wok used to cook the pork and leave to simmer for 1-2 minutes, or until the sauce has reduced to a thick consistency. Season, to taste, with gluten free soy sauce, rice wine and ground white pepper. To serve, pour the sauce over the pork and serve with rice and choi sum.