We got a giant head of napa cabbage two weeks ago, and then before it was finished we got another one last week. So I've been on a quest to use up the cabbage creatively that ended up in a recipe I'm pretty happy with.
for every 4 cups of sliced napa cabbage
2 tbsp balsamic vinegar
1 tsp soy sauce
1 tsp sugar
1/2 tsp salt
1 tsp sesame oil
1 tbsp plain vegetable oil (we use safflower, but you could use canola, sunflower, etc.)
I don't usually measure while I'm making salad dressings, so taste this and feel free adjust a little to taste - more sugar if it's too sweet, more soy sauce if it's not salty enough, more sesame oil if you can't taste it, etc.
Add whatever else inspires you (or whatever else you've got too much of in the fridge!) to the salad. Last night's version had some sliced sugar snap peas, some shredded arugula, and some scallions. If you want to make it a main dish, you could add the protein of your choice and more vegetables with a little more density than cabbage and leafy greens.
Which brings me to another tip - in addition to finding simple recipes you like with a vegetable you have a lot of, sharing it with friends is a great way to use more of it before it gets a little repetitive on your table. Last night's cabbage salad went to a potluck dinner. We've got about 2 servings left, and it keeps well enough that they should work for tonight's dinner.