Know your butcher and respect the animal
Anyone who wants to eat meat sustainably should be aware that meat comes from an animal that is bred, grows up, is fed and at some point is slaughtered and processed into meat and sausage. Once upon a time, that peice of meat was a living being that grew up and someone tended to it.
That's why it is important that you build up a good relationship with your butcher. Ask him questions about the origin and supply chain.
Or find a supplier where you can be sure that all information is correct. Ideally, you can visit the farmer where the animals you want to eat are bred.
If you want to do it right, you should not hesitate to use and eat all the ingredients of an animal or even be present at a slaughter. That means: no fear of the innards and extremities, like kidneys, thighs, feet etc. Cattle does not only consist of the steak or the burger, which you can buy already packed in the freezer. Remember: Once it was a whole, living animal. And eating whole animals is not about blood and guts, but about enough respect for the animal to realize that when it died for you, you can at least use every part.
Little meat is good.
It is even more sustainable if you reduce your meat consumption to a minimum. 1-2 times a week is fine. Less is better.
No meat is even better.
For a very climate-friendly cuisine, however, it is much better to do without a large amounts of animal products. Especially pigs and cattle have a bad climate footprint, because they are bred in large masses. Cattle release methane during their digestion. In addition, pigs and cattle consume an enormous amount of fodder, for whose cultivation forests are cleared. In addition, new trade agreements mean that meat products are sold across the globe. China buys pigs from Germany. Germany buys cattle from Argentina. This increases the global CO2 emissions enormously.
So if you want to do something for the climate, buy regional organic meat or do without it completely.