My mom had to become a sort of vegetarian, and to this day when I see her (about every other year, whereas I used to cook for her and Dad every weekend) she wants my grilled ratatouille (her name for it).
I take all the vegs you can think of for ratatouille -- squash (any and all kinds), onions, eggplant (aubergine), tomatoes, you name it. I cut in such a way that they will not fall through the grill on the "barbecue pit" (I know it's called other things now), then toss in olive oil and Cavendar's Greek seasoning (use any garlic based seasoning you like) and lots of fresh ground black pepper. I then grill the vegs. Usually I'm going to grill some meat right after, but I do the vegs first, then place in a large bowl, and chop to large, but easily eaten pieces. I serve as a side dish for that meal, but always make enough for leftovers. I then use the leftovers to toss with pasta as a second meal. Mom would eat the vegs as her entire meal.
These vegetables make a great base for soups as well .... you can actually fool folk into believing they are eating a bean or pea soup that has smoked meat in it if you cook over charcoal. Chop the vegs quite finely, and they will dissapear into a thick soup, just leaving a great smokey flavor.