Spicy Korean Ribs

Name: Spicy Korean Ribs
Ingredients: 4 racks baby back pork ribs; salt and ground black pepper to taste; 1 small onion, sliced; 1 cup kochujang (Korean hot sauce); 0.25 cup white vinegar; 0.25 cup minced garlic; 3 tablespoons sesame oil; 2 tablespoons soy sauce; 1 (1 1/2 inch) piece fresh ginger root, minced, or to taste; 1 (1 1/2 inch) piece fresh ginger root, sliced, or to taste; 1 (12 fluid ounce) bottle pilsner-style lager; 1.5 teaspoons toasted white sesame seeds; 1.5 teaspoons toasted black sesame seeds