Pork loin with Guinness sauce

1kg pork loin
2 pints of Guinness1 cup beef stock
2 onions, Slices
4 carrots, in cubes
1 garlic clove, chopped
1/2 cup chopped bacon
3 little pieces of dried porcini mushroom (optional);
Chopped rosemary
2 tbsp butter

1. In a big pan brown the pork loin with the butter;
2. Take the meat away and brown all the vegetables, mushrooms with the bacon;
3. Add the meat back, the beer, stock and herbs;
4. Cook in low heat for about 1 hour;
5. Remove the meat and blend all the other ingredients until smooth;
6. Cook the meat again on that sauce for about 30 minutes;
7. Slice the meat and serve it.