To prepare a Spanish style pork shoulder steaks recipe, first you will need to cut the shoulder of pork in half lengthwise. Then, place the cut side down on the cutting board. Cut the pork into 12 inch thick slices. Place the slices in the refrigerator to marinate for at least 1 hour. Heat the olive oil over medium-high heat. When the oil is hot, add the chopped onion and garlic. Cook until the onion is translucent, about 5 minutes. Add the sliced pork and cook, stirring occasionally, until browned on all sides, 2 to 3 minutes more. Remove from the heat and set aside to rest. While the meat is resting, prepare the seasonings. Toss the ground cumin, paprika, oregano, salt and pepper to taste. Pour the marinade over the steak and let it sit for 10 minutes to allow the flavors to meld. Serve with sour cream and guacamole.