Slivers of fresh onions, slivers of fresh peppers, some thin slices of cauliflower, thin slices of fresh green beans... and shred the romaine lettuce. Heat up some oil in a skillet wok. Add the denser vegetables at first and start stirring while they fry - the cauliflower, or some thin slices of fresh carrot, cut on the diagonal. When these have been cooking for a while at high heat, then you can add the peppers, green beans, onions, etc. and FINALLY the lettuce. The lettuce cooks so quickly - you want it to have some crunch, still - that you can add some stir-fry-sauce (Kikomann makes a stir-fry sauce that is good, but use as little as you can get away with) at the same time as the lettuce. Stir and cook just enough to season and serve hot over some cooked brown rice.
If you want to avoid the bottled stuff, you can make your own sauce by adding a little sesame oil to flavor, some soy sauce, some sugar or honey, some fish sauce if you use it sparingly, and some ginger (you can buy it already sliced and in a jar, or you can peel the fresh ginger and chop it yourself - fresher and better tasting but more work).
If you're making an asian-style soup, shredded lettuce is delicious as a last-minute addition to the pot. Same ingredients as above but cook it all in broth - any flavor broth - and then add some light (lite) canned coconut milk last, and just heat it up. Very good!