How to Make It
In a large enameled cast-iron casserole, bring the Smoky Pork Stock to a boil. Add the collard greens and cook over moderately high heat until tender, 30 to 40 minutes. Drain the greens, reserving the liquid.
Wipe out the casserole. Add the oil and onions and cook over moderate heat until translucent, 5 to 6 minutes. Add the garlic, crushed red pepper and 1/2 teaspoon each of salt and black pepper. Cook, stirring, for 1 minute. Add the tomatoes and 3 cups of the reserved cooking liquid and simmer over moderately low heat until the tomatoes begin to break down, about 15 minutes. Add the collard greens and cook until heated through, about 5 minutes.