Step 1
Heat oven to 300 degrees. Score meat’s skin with a sharp knife, making a cross-hatch pattern. Pulse garlic, onion, oregano, cumin, chili, salt and pepper together in a food processor, adding oil in a drizzle and scraping down sides as necessary, until mixture is pasty. (Alternatively, mash ingredients in a mortar and pestle.) Blend in the vinegar.