This keeps the vegetables away from direct heat, uses only a minimal of oil, no charring, keeping the integrity of the vegetables intact. You can magnify the steaming effect by adding a little vegetable stock instead of oil and leave it on the grill a minute or two less than suggested.
You can do family style or individual packets. Make sure you use heavy duty aluminum or double up on the layers. Keep the tinfoil vented higher for more of a steam action or flat packaged for more of a grill effect. Great way to cook greens like swiss chard, asparagus, cremini mushrooms, practically any vegetable but experiment especially the ones that that tend to fall into the charcoal. Here are some ideas:
One bunch of chopped swiss chard, kale, leafy spinach or beet greens, sliced small red onion, 2 sliced garlic cloves, pinch of crushed red pepper, stalk of rosemary, s/p , drizzle of extra virgin olive oil or dab of butter. 8 min.
One bunch chopped kale, 1 large sweet potato, kabocha or butternut squash, peeled and 1” cubes, 1 small chopped onion, 2 minced garlic cloves, thyme sprigs, s/p, drizzle of extra virgin olive oil. 10 to 15 min.
1 pint cremini mushrooms, 2 minced garlic cloves, handful chopped parsley, pinch crushed red pepper, thyme sprigs, drizzle of olive oil and drizzle of nama shoyu or balsamic vinegar. 6-8 min.
1 pint halved cherry tomatoes, 2 minced garlic, handful chopped basil, s/p, drizzle of ev olive oil. This could stay on the grill and slow roast for as long as 20 min if you keep it away from the main heat.
2/3 zucchini and or yellow squash , chopped, wedged, or sliced, handful chopped basil and mint, zest of a lemon, s/p, drizzle of ev olive oil. 8-10 min.
1 bunch asparagus, handful sliced shitake mushrooms, zest of lemon, fresh oregano leaves, dab of butter, s/p. 5 min.