This could become one of your grilling favorites.
First you need to steady the onion by slicing off the root end, as evenly as you can.
Mine usually have a little lilt to them, but no too bad.
Place onion on aluminum foil.
At this point you can add any seasonings you like. Some people add BBQ sauce, or Worcestershire sauce, or their favorite grill seasonings, the possibilities are endless.
Bring the aluminum foil up, around and totally enclose the onion, keeping the onion upright at all times. Be sure and crimp the foil edges real good to prevent any leaking.
For insurance, I double wrap the onion.
Spread the coals evenly in the grill and place the onion, on the grate over the coals. I put it right in the middle of the grill.
If you make this onion while camping, just gently place it along the outside 1/4 of the fire. Using very, long, tongs, turn it every 15 minutes.
Depending on the fire, this should take anywhere from 1/2 to 3/4 of an hour to become sweet and juicy.
Grill your favorite meat on the coals and you are set.
And that's that