Spicy Pork Stew

Name: Spicy Pork Stew
Cuisine: American, Indian
Ingredients: 2 lb. boneless pork butt; 2 tbsp. cider vinegar; 1 tbsp. vegetable oil; coarse salt and freshly ground black pepper; 1 medium red onion; 1 tbsp. finely chopped garlic; 1 tbsp. cocoa powder; 1 tsp. ground cumin; 1 tsp. ground cinnamon; 1 tsp. ground cardamom; 1/4 c. coarsely chopped chipotle chiles in adobo sauce; 1 sweet potato; 1 medium turnip; Cooked basmati rice (optional); 1 plum tomato; coarsely chopped fresh cilantro