Miso Ramen With Crispy Pork and Burnt Garlic-Sesame Oil Recipe

3 pounds pig trotters, split lengthwise or cut crosswise into 1-inch disks (as your butcher to do this for you) 2 pounds chicken backs and carcasses, skin and excess fat removed 2 tablespoons vegetable oil 1 large onion, skin on, roughly chopped 12 clove garlic cloves One 3-inch knob ginger, roughly …