Recite then blow on the meat before consumption. It will purify the meat and it will bring the benefit of liberation to the being. The mantra will transform the meat to nectar and create extensive generosity and merits so it becomes a cause for enlightenment. One will not commit heavy negative karma of eating the meat rather one will bring great benefit to the being the meat belongs to.
Om Ah Bira Khe Tsara Hum (7x)
Some people may argue that with this mantra, it encourages people to eat meat because now even if you eat meat, you will still be blessed. I think this is more for occasions when you have no choice but to eat meat, so it is up to individual whether they believe in this mantra or not.