I agree with Tessa - I cook it fairly much the same when trying to keep fat intake down. Finely slice it, into frying pan with a little chicken stock, water, salt, pepper, maybe a pinch of sugar if you are allowed (or substitute), fry off till a little wilted but still crunchy. Enjoy it as a base for some steamed fish or boneless skinless chicken. Maybe some light soy sauce splashed on at last moment, plus any fresh herbs you prefer.
Or poached sliced cabbage as a soup - simmering low fat chicken stock, season this with fish sauce, soy, garlic, ginger, chopped chilli, add cabbage and some sliced mushrooms, simmer 5 mins, take off the heat, swirl in an egg white, serve over chopped spring onions/green onions. Eat it straight away or the mushrooms can get rubbery, same with the egg white.
You could also use whole cabbage leaves, blanched in boiling water for a minute or so until just tender, to wrap other foods you are allowed, such as shredded carrot, mung bean sprouts, shredded steamed chicken fillet, sliced steamed fish, fresh herbs, finely sliced bell peppers/ capsicums. Put some filling inside each leaf, roll 'em up, steam for few minutes - yum. Use a light soy or sweet chilli sauce for dipping if liked, or greek yoghurt or tzatziki.