Braised Short Ribs with Celery Root Purée

Name: Braised Short Ribs with Celery Root Purée
Ingredients: 3 tbsp. olive oil; 3 lb. bone-in short ribs; Kosher salt and freshly ground black pepper, to taste; 1⁄4 cup unsweetened cocoa powder; 5 cloves garlic, smashed; 2 stalks celery, chopped; 1 large yellow onion, chopped; 1 medium carrot, chopped; 1⁄4 cup tomato paste; 3 cups full-bodied red wine, such as nero d’avola; 2 cups beef stock; 3 sticks cinnamon; 2 bay leaves; 2 sprigs sage; 2 whole cloves; 1 bunch thyme; 1 star anise; 2 tbsp. unsalted butter; 3 tbsp. pomegranate seeds; 1⁄2 cup microgreens, such as arugula