Put all the ingredients in a wide 6-to 7-quart heavy pot (don''t worry if the pork is not completely covered) and bring the water to a boil, skimming the surface as necessary. Lower the heat and simmer vigorously, stirring occasionally, until the pork is fork-tender and the liquid has completely evaporated, 1½ to 2 hours. Discard the orange pieces and bay leaves. If the liquid hasn''t evaporated after 2 hours, transfer the pork pieces to a bowl and let the liquid continue to bubble away, stirring often, until it has.
Preheat the oven to 450°F. Transfer the pork and fat to an ovenproof dish, if necessary, and brown the pork, uncovered, in the oven for 20 to 30 minutes. There''s no need to stir.
Carnitas keeps in the refrigerator for up to three days.