Preheat the grill. If using charcoal, set up a two-stage fire with direct and indirect heat.

Chop the heads of Romaine in half lengthwise. Be sure to leave the stem, lest the leaves separate.

Distribute the oil over the Romaine, being sure to get it in between leaves where possible.

Remove the outermost skin of the onions and chop in half along the “equator”, leaving the ends on.

Once the grill is ready, put the onions cut side down over indirect heat. Let grill for at least 15 minutes, longer if possible.

Once you are about 5 minutes from done, put the heads of Romaine cut side down over direct heat. Grill for 1 or 2 minutes until starting to char. Flip, and grill for another 1-2 minutes. Remove from heat.

Place the onions over direct heat for 1-2 minutes, flipping halfway through, to ensure some charring. Remove from heat.

Roughly chop the lettuce and add to salad bowl. Remove the outermost layer of the onion, then chop the remaining onion and add to salad bowl. Toss with tomatoes and feta.