In a pan, heat oil to medium-high heat. Add pork and cook, stirring occasionally, until meat browns.
Add garlic and fried shallots to the pan and cook until fragrant. Add the five-spice powder, sugar, soy sauces, rice wine, and just enough water to cover the meat. Then, bring to a boil. Reduce heat to a gentle simmer and cover partially. Cook until meat is completely tender and sauce has thickened, 3 to 4 hours. Add pickled sour mustard.