6 tablespoons cider vinegar
2 tablespoons rice vinegar
1/4 cup dark soy sauce
1 tablespoon sugar
3 lb pork spare ribs, on the bone, cut into 1 1/2 inch square pieces
2 tablespoons Dijon mustard
Coarsely cracked black pepper
Kosher salt (optional)

6 tablespoons cider vinegar 2 tablespoons rice vinegar 1/4 cup dark soy sauce 1 tablespoon sugar 3 lb pork spare ribs, on the bone, cut into 1 1/2 inch square pieces 2 tablespoons Dijon mustard

1. Cook the ribs: In a large saucepan, combine 2/3 cup water, the cider and rice vinegar, soy sauce, and sugar. Bring to a simmer, stir to dissolve the sugar, and add the spare ribs. Stir to separate the pieces so they are all coated with the liquid. Cover and simmer over low heat, stirring from time to time, until the meat is tender and starting to separate from the bone, 1 hour to 1 hour 15 minutes

2. Finish the Sauce: Scoop out the ribs to a serving bowl and keep warm. Add the mustard to the cooking liquid and simmer to reduce it until thickish, 5 to 10 minutes. Pour the sauce over the ribs and gently toss them in the sauce to coat each one. Taste for seasoning. Sprinkle with pepper (and salt if needed), and serve immediately