Some meats have long simmering before it is cooked (for example, pulled meat). If the cooking water should be complemented interim, do it always with warm / hot water. Then the meat is nice and tender (cold water the meat is chewy).
The meat remains tender if something sour will be cooked, eg (balsamic) vinegar, tomatoes (puree).
A sliced onion does wonders when pulled. The meat is well cooked and much better from. This is also a very good piece of loin.
With braised (pulled) a carrot. Get a delicious gravy.
Also delicious ... simmer with a slice of gingerbread!
To get delicious braised, prick some cloves into the meat and put a bay leaf there. A little vinegar with it and you get delicious braised.
To the cloves to be able to easily find back, puncture this in a cut onion.
At the end of the cooking time you take out the onion and you also immediately grab the sticks of cloves!