1 ½ cups apple cider
1 cup dark brown sugar
1 tablespoon yellow mustard seed
2 tablespoons Dijon mustard
½ cup tomato paste
¼ teaspoon salt
¼ teaspoon fresh ground black pepper
2 smoked pork neck bones
Combine the cider vinegar, apple cider, brown sugar, mustard seed, Dijon mustard, tomato paste, salt, black pepper, and neck bones in a heavy-bottomed saucepan over medium heat; simmer until the sauce thickens, 30 to 40 minutes. Skim any foam from the surface of the liquid and discard. Remove and discard the neck bones. Cool the sauce to room temperature or use immediately.