Serves 8 to 10 people
3 large sweet Vidalia or Walla Walla onions, halved and sliced into ½-inch-thick half moons
3 tablespoons, plus ½ cup extra-virgin olive oil
12 ears fresh sweet corn, shucked
1 cup fresh lemon basil leaves
4 jalapeño peppers, cored, seeded, and sliced paper-thin
Grated zest and juice of 3 lemons
2 teaspoons sugar
Salt and freshly ground black pepper
Preheat the oven to 450 degrees F.
Spread the onions on a rimmed baking sheet and drizzle with the 3 tablespoons of olive oil. Bake in the oven until tender, about 15 minutes, then remove and transfer to a large bowl, carefully scraping the bottom of the baking sheet to get all of the onions and their juices.
Place the corn on the same baking sheet and drizzle with ¼ cup of olive oil. Roast in the oven, turning it occasionally, until just starting to brown, about 20 minutes. Remove, and allow to cool.
Using a serrated knife, trim the kernels from the roasted corn and add them to the onions in the bowl. Add the lemon basil and the jalapeños, and mix well. Add the remaining ¼ cup of oil, the lemon zest and juice, and the sugar.
Toss and season to taste with salt and pepper. Mix gently but thoroughly.