2) Lightly grill the tomatillos over an open flame until lightly charred. Remove from the heat, place in a bowl and cover with cling film to keep warm for 20 minutes.
3) Add the pork shoulder cubes to the casserole or Dutch oven and cook over a high heat until browned on all sides.
4) Add the onion-pepper mixture and tomatillos to the pork. Mix thoroughly and then deglaze with white wine and vinegar. Leave to reduce for 5 minutes, then add the chicken stock, oregano, cumin, salt and pepper.
5) Allow to simmer for 1 hour and then serve with your choice of garnishes, such as sour cream.