My Goals

  • Tender, intact onions

  • Lots of char and caramelization

  • A flavorful finish

While grilled onions are typically used as part of a grilled vegetable mix, their sharp, sweet bite; caramelized edges; and crisp-tender texture are so good that I wondered if I could create a version worthy of being a side dish all on its own. I’d opt for the common yellow variety and would serve onion halves, rather than separating them into rings or cutting them into wedges, since I wanted a substantial side dish that presented well. The trick would be figuring out how to cook them evenly. To serve the onions as a stand-alone dish, I wanted to cook them longer in order to mellow their sharp bite and soften their texture. I would have to figure out how to achieve this without burning their exteriors.

To that end, medium heat was my best bet for giving the halves enough time to cook through without burning. But simply putting the onion halves on the grill and cooking them until charred and tender left a lot to be desired. The onions had dried out too much and required frequent turning to make sure they didn’t burn. And with all the handling, they came apart by the time they were done.

Our five-recipe test included a range of onion varieties and methods of preparation, but we decided that versatile yellow onion’s strong but mellow flavor made it a perfect candidate for our side dish.

My first change was to modify the way I prepped them. Following the lead of other recipes I’d found, I had been cutting the onions crosswise through the middle. But cut this way, they had no chance of holding together—the rings toward the center popped right out. Cutting them from pole to pole (in other words, from root end to stem end) gave each half a better chance of staying in one piece.

To prevent them from drying out too much, I tried wrapping each half in foil before grilling; I hoped that the onions would cook through gently in the moist heat while developing some browning through the foil. Indeed, these onions were very tender, but the flat side, which had been facing the grate, bordered on burnt. And even worse, they lacked any charred flavor from the grill since they hadn’t been directly exposed to the flames.

Failed Test

Cooking whole onions in the coals makes them taste steamed versus grilled.

I needed a hybrid approach. I scrapped the fussy individual packets and instead arranged the halves cut side down in an aluminum roasting pan. And to keep the exteriors from charring, I left the skins on. I covered the pan and let the onions cook until they were softened before transferring them to the grill grate to finish cooking. Unfortunately, there was so much residual moisture from the steaming that the onions didn’t pick up much char, and they were difficult to handle since they were so soft.

After grilling the onion halves facedown on the grate, we transfer them to an aluminum pan and steam them, covered, on the grill until cooked through.

So I reversed the order. I began grilling the halves cut side down on the grate until charred. Then I transferred them cut side up to the pan, covered the pan, and let them steam until a paring knife slipped easily in and out of each half. These onions held together and had a buttery-rich texture, with great caramelization on the bottom side that had been against the pan. But the char, though impressive going into the pan, had washed out a bit in the steamy environment. The fix was twofold: I left the onions cut side down on the grate for several minutes to bolster the char, and I briefly grilled the rounded side over direct heat, too.

The last piece of the puzzle was to create a dressing that would complement the smoky-sweet flavor of the onions.

My tender, caramelized, smoky onions just needed a quick, flavorful finish. An herb-flecked butter seemed promising, but the richness overwhelmed the onions. Instead, I whisked together a simple balsamic vinaigrette to drizzle over the onions before serving. The dressing complemented their sweetness and provided some necessary contrasting acidity. With a final sprinkling of minced chives, I had grilled onions well worthy of side-dish status.

Keys to Success

  • Tender, intact onions

    Cutting the onions in half from root end to stem end helped them hold together on the grill. Cooking them directly on the grate to develop char and then cooking them through in a covered disposable pan made them tender throughout and minimized handling.
  • Lots of char and caramelization

    Halved onions provided a flat surface for developing lots of char. We left them cut side down over the direct heat until they were well browned and then grilled the rounded sides over direct heat for a few minutes to get even more char. As the onions steamed, the bottom portion in contact with the pan caramelized; leaving the skins on ensured that the onions didn’t burn.
  • A flavorful finish

    A balsamic vinaigrette lent bright acidity and flavor that complemented the chargrilled, sweetly caramelized onions, while a sprinkling of minced chives brought color and freshness.