Heat the oil in a deep pan or stockpot set over medium-high heat. Stir in the onions and garlic, and cook until transparent, about 5 minutes. Mix in the Napa cabbage; toss and cook until wilted, about 2 minutes. Add the ham hocks, cayenne pepper, bay leaf, Cajun seasoning, and salt, stirring for 2 minutes more. Pour in the chicken stock and black-eyed peas. Bring the mixture to a boil, then reduce heat to low and cook uncovered for 2 hours.
Meanwhile, place the rice and water into a saucepan. Bring to a boil, reduce heat to low, cover, and simmer until all liquid is absorbed and rice is light and fluffy, about 20 minutes.
Before serving, remove the ham hocks from the pot. Coarsely chop the meat, and return to the black-eyed pea mixture. Serve hot over Basmati rice.