How to Make It
Season the pork with salt and pepper. In a large enameled cast-iron casserole, heat the oil until shimmering. Add half the pork and cook over moderately high heat, turning occasionally, until browned all over, about 8 minutes. Using a slotted spoon, transfer to a plate. Repeat with the remaining pork.
Add the chopped onion, chopped garlic and a generous pinch of salt to the casserole. Cook over moderate heat, stirring occasionally, until softened and lightly browned, 5 to 7 minutes. Stir in the tomatoes, chipotles, chili powder, cumin and oregano and cook until bubbling. Stir in the stock and bring to a boil over high heat. Stir in the pork, cover and simmer over low heat until tender, about 1 hour.
Meanwhile, in a large saucepan, combine the black-eyed peas with the quartered onion, whole garlic cloves and 12 cups of water. Bring to a boil, then simmer over low heat until the peas are tender, about 45 minutes. Remove from the heat, add 1 tablespoon of salt and let stand for 5 minutes. Drain well and discard the onion and garlic.
Stir the collard greens into the stew in large handfuls, letting each handful wilt slightly before adding more. Cover and simmer over low until the pork is very tender and the collards are just softened, about 20 minutes. Stir in the peas, cover and simmer until hot, about 5 minutes. Ladle into bowls and serve.