Tie pork with kitchen twine so that it retains its shape during cooking and season with salt and pepper.
In a large enameled pot or casserole dish, add oil and vinegar, garlic, rosemary and juniper berries.
Add meat to the pot and marinate for 24 hours. Mix pork and marinade occasionally during the resting time.
Then add milk to the pot until meat is covered. Simmer over low heat for about 1 hour. At the end of cooking, milk should have been completely absorbed (otherwise drain).
Finally, increase the temperature and brown meat on all sides.
Remove kitchen twine before serving.
Can also be served cold.