In a bowl, combine the oregano, black pepper, fresh thyme, cumin, crumbled chicken bouillon cube, orange juice, lime juice, olive oil, and white vinegar. Stir well to create a marinade.
Peel and crush or finely chop the garlic cloves. Stir the garlic into the marinade.
Place the pork shoulder, skin side up, in a roasting pan. Rub the marinade all over the pork, making sure to coat all sides evenly.
Cover the pan with foil and refrigerate. Marinate for at least 3 hours, or overnight for best results.
Remove the marinated pork from the fridge 30 minutes before cooking to bring it to room temperature.
Preheat your oven to 350°F and bake the covered pork, skin side up, in the preheated oven for 4 to 5 hours, or until tender.
To crisp the skin, increase the oven temperature to 375°F. Remove the foil and continue to bake for an additional 45 to 60 minutes, or until the skin is crisp and golden brown.
Transfer the cooked pork to a cutting board and let it rest for 10 minutes before slicing.