I'm right there with you (except for the garden part). But I'm not sure I'll be much help, b/c we like just about everything. We usually simply add olive oil & sea salt to such things as bell peppers, zucchini, summer squash, mushrooms, asparagus. I use a basket with a handle for easy flipping.

Other odds & ends: sliced white onion can accompany grilled steak. Sliced tomato sprinkled afterwards with parmesan is good. It's also fun to slice potatoes and white onion, mix in a ketchup or Asian sauce, and grill them in a foil pouch.

There are lots of possibilities & I've always felt we were just scratching the surface. I have an uncle that's a vegetarian & he loves to grill.