aint a recipe, but simply chucking olive oil, S&P or whatever other spices you want to shake on the following veggies and putting them on a grill is elite:

Capsicum/peppers
Zucchini sliced the long way
Eggplant
thick onion ring (if on a grill grate - ofc if you have a flat plate, you're gonna slice thinner and/or do sliced halves and caramelise the fuck outta those onions)
Asparagus
Jacket/baked potato (wrap in foil and bake for ages, can bury under coals if you're cooking with actual fire or at a campfire)
Mushrooms
Corn (whole cob or 'corn ribs')

also grilled fruits can go hard:
pineapple
banana sliced lengthways