Wahaca's famous pork pibil | Wahaca

Name: Wahaca's famous pork pibil | Wahaca
Cuisine: American, Latin American, Cuban
Ingredients: 1tsp allspice berries; 2tsp ground cumin seeds; ½tsp cloves; 1tsp peppercorns; 100g achiote paste; 3tbsp cider vinegar; 1 medium onion, coarsely chopped; 3 garlic cloves, coarsely chopped; large bunch of fresh oregano or 1tsp dried oregano; 3 fresh bay leaves; 2tbsp sea salt; 3tbsp olive oil; juice of 6 oranges (about 450ml); 1.5kg neck of pork, cut into a few large pieces; 1 habañero or Scotch bonnet pepper, deseeded and finely chopped; 25g butter