Make the marinade by combining HP sauce, garlic powder, black pepper, cornflour, sugar, oil and water together in a bowl.
Lightly pound the pork chops and coat in the marinade. Let sit for 20 minutes.
Meanwhile, make the sauce. Mix together the red wine, balsamic vinegar, tomato ketchup, Worcestershire sauce and sugar in a bowl. Set aside.
In a large frying pan, heat the 1 tablespoon oil over high heat. Fry the pork chops until they are brown on both sides, about 3-5 minutes. Reduce the heat to medium-low and continue to fry the pork chops until cooked through, about 3-5 minutes more. Set aside on a kitchen towel lined plate.
Heat the same frying pan with 15g butter and saute the garlic until fragrant, about 2-3 minutes. Add onion and stir-fry with a little salt until soft, 2-3 minutes. Add the mushrooms and stir-fry for 1-2 minutes.
Add the tomatoes and sugar to the pan and stir until the ingredients have heated through, about 2-3 minutes. Stir in the sauce and pork chops, stir and allow to heat through, 2-3 minutes. Serve hot.