Chinese Roast Pork

Name: Chinese Roast Pork
Ingredients: 4lb pounds pork shoulder roast; 3 tablespoons Chinese five-spice powder; 1/2 tablespoon ground black pepper; 2 tablespoons peanut or canola or corn oil; 1 medium onion, chopped fine; 1 tablespoon minced ginger; 3 garlic cloves, minced; 2 tablespoons vegetable oil; 3 tablespoons mirin; 2 tablespoons rice wine vinegar; 1/4 cup Pad Thai sauce; 1 teaspoon sriracha (or to taste); 2 teaspoons sesame oil; 2 tablespoons light soy sauce or tamari; 2 tablespoons creamy peanut butter; 1/2 cup chicken stock