Step 3
While pork is marinating, combine pineapple, onion, vinegar, brown sugar, pineapple juice, ginger, serrano chiles, garlic, mustard seeds, and salt in a large saucepan; bring to a slow, simmering boil. Reduce heat to low; simmer until thickened, about 45 minutes, stirring every 5 to 10 minutes. Off heat, stir in golden raisins; cool slightly, 10 to 15 minutes.