I know... it sounds weird, most of us are put-off when the lettuce goes all wilty in a sandwich, but when the right kind of lettuce is quickly sauteed over high heat it makes a delicious vegetable side dish. It retains its crisp texture and the greens become almost fluorescent in color. The part I like best is that the bitterness of the lettuce fades away while the sweetness is brought forward.
When cooking lettuce it's important to use the right kind. Soft pillowy lettuce like butterleaf isn't well suited for being cooked. Your best bet is to use crisp lettuce with a firm stem like Romaine or Iceberg. While iceberg will work just fine, I tend to find its flavor almost non-existent, so really you just want to get a nice head of Romaine lettuce.
As for seasonings, you could go "Italian" with some olive oil, salt and pepper and a squeeze of lemon to serve, or "Chinese" with a dollop of oyster sauce, or in my case, I used the braising liquid from my buta kakuni with a bit of cornstarch for a more "Japanese" flavor.
- Dissolve the cornstarch and white pepper in the braising liquid.
- Get a saute pan very hot over high heat then add the oil. Quickly add the lettuce to the pan. The leaves should keep the oil from spattering too much, but be careful none-the-less.
- Use the pan to toss the lettuce until it is bright green (about a minute). Add the liquid, tossing to coat. As soon as the sauce thickens (shouldn't take more than a couple tosses) it's done and should be served immediately (if it sits, it will get watery and soggy).