1- In the serving dish, water with olive oil and arrange the meat, with the tip of a knife, make holes in the meat so that the seasoning penetrates better. Season it well with vinegar, garlic, oregano, salt, black pepper and green onions on both sides.
2 – Leave to marinate for approximately 2 hours in the refrigerator.
3- Peel the potatoes, or if you prefer you can keep the peel to a more rustic style, and cut in 4 pieces, season with salt, black pepper, oregano and olive oil. Reserve.
4- Remove the meat from the refrigerator and sprinkle with olive oil, arrange the seasoned potatoes and cover with foil.
5- Bake in preheated oven 200 ° for approximately 40 minutes.
6- Remove the foil, put the butter on the meat and return it to the oven at 180 ° – 200 ° for about another 20 – 30 minutes, or until it is at the point of your preference, the meat should be juicy, you should control so that it does not exceed the point.
7- Remove from the oven and let the meat rest 5 minutes to start slicing.
8 – Arrange the slices on the serving plate with the potatoes. Serve next.