Heat oil in a large wide heavy pot over medium-high.
Add half of the pork to pot, breaking apart into 6–8 large chunks with a wooden spoon.
Cook, undisturbed, until well-browned underneath, about 5 minutes.
Turn pieces and continue to cook, turning occasionally, until pork is browned on 2–3 sides, about 5 minutes longer.
Add ginger, garlic, sugar, and remaining pork to pot and cook, breaking up pork into small clumps, until meat is nearly cooked through, about 5 minutes longer.
Add tomato paste and 2 basil sprigs.
Cook, stirring occasionally, until paste darkens, about 2 minutes.
Add chili paste, soy sauce, vinegar, and 2 cups of water.
Bring to a simmer, reduce heat to low, and cook, uncovered and stirring occasionally, until sauce is slightly thickened and flavors have melded, 30–45 minutes.