Wash salt meat and place in the pot with seasonings and herbs. Add three cups of water making sure salt meat fully emerged, add more water if necessary. Wash peas, discarding of any bad ones, and add to pot. Bring to a boil and cook until peas are tender. Wash and drain rice and add to the pot, along with the remaining water, lime juice, chopped onion and margarine. Cover saucepan and boil over moderate heat, then allow to steam over low heat until the water is absorbed and rice grains are tender.