During the months when the produce aisle seems a bit bare (no locally grown tomatoes or piles of fresh corn in sight), take advantage of the ever-growing variety of root vegetables that are showing up everywhere. Rough, rustic, and roasted, the root vegetables featured in this dish are filling, comforting, and nutritious.
This dish combines parsnips and cipollines. Also referred to as wild onions, fresh cipollines are the bittersweet bulbs of the grape hyacinth, and are available for a short time in the fall. If you can't find them, use some other sweet onion, such as Vidalias, cutting them into walnut-size pieces.
Slow-cooking onions in olive oil brings out their sweetness, which is offset by the acidity of the tomatoes and vinegar. This confit is wonderful with grilled meats. You'll want to keep some on hand all summer.