Cut the pork into strips about 1cm wide, then peel and crush the garlic. Put both in a bowl, toss with the soy, rice wine, salt and five-spice powder (if using), cover and leave to marinate for at least 30 minutes (cover and put in the fridge if you’re leaving it to sit for longer).
While the pork sits, prepare the sauce by stirring the preserves, then add the citrus juice and sugar. Stir until the sugar dissolves, then mix in the vinegar, soy and 90ml water. Season to taste, adding more sugar, if you like.
Use another small bowl to stir the cornflour into a teaspoon of cold water.
Cut the onion and pepper into chunky diamonds, separating the onion layers as you go. Slice the chilli into rings.
If you like, add other vegetables to the mix, too (tenderstem broccoli or mangetout would be nice); just make sure they’re sliced thinly enough to stir-fry without overcooking the other ingredients.
Beat the egg in a bowl, gradually whisk this into 60g cornflour until you have a smooth batter, then season.
Spread some more cornflour on a plate, then put both the bowl and plate near the hob. Add another tablespoon of cornflour to the marinated pork, and toss until the meat is coated.
Pour enough neutral oil into a large pan, wok or fryer to fill it by a third, then heat it up to 180C (digital thermometers are cheaper than oil and will ensure you get good results). Once the oil is nearly at temperature, dunk the pork in the batter, then shake off any excess and roll it in the plate of cornflour to coat.
Fry the pork in the hot oil for three minutes, until golden (it will be fried again later, so don’t go too dark at this point or you’ll overcook the meat), then lift out with a slotted spoon and drain on kitchen paper.
Keep the oil warm on a low heat while you make the sauce. Heat a tablespoon of neutral oil in a wok until smoking, then stir-fry the onion, pepper and chilli until softened.
Tip in the sauce mixture, bring to a boil, then stir in the cornflour-and-water mixture and cook until the mix thickens. Add the pineapple, turn down the heat to low, and keep warm.
Heat the same pork oil to 190C and fry the meat again, this time for just 30 seconds, until golden brown. Scoop out with a slotted spoon and transfer to the sauce. Turn up the heat, toss to combine, then tip out on to a platter.
Serve with egg-fried rice and perhaps something fresh and green.
