Bring out the flavors of onions, zucchini, corn and more by grilling them and add a burst of smoky sweetness to this spring salad that goes great with our Shallot and Sherry-Wine Vinaigrette.
Heat a grill or grill pan until medium hot. Have ready 2 long metal skewers. Place onions in a heat-proof bowl, and cover with boiling water. Let stand 5 minutes. Drain in a colander, and let stand until cool enough to handle. Remove and discard skins.
Place corn on grill, and cook, turning, until kernels are slightly charred on all sides, 10 to 12 minutes. Remove corn from grill. Using a sharp knife, cut kernels form cobs. Set kernels aside, and discard cobs.
Thread the pearl onions on the skewers. Brush squash, zucchini, and onions generously with olive oil; season with salt and pepper. Place oiled vegetables on grill, and grill until slightly charred on all sides, 3 to 4 minutes for the zucchini, 6 to 8 minutes for the onions. Transfer the vegetables to a cutting board.
Cut the squash and zucchini into 1/2-inch dice, and place in a large bowl. Remove onions from the skewers, and add to bowl.
Add reserved corn, cucumbers, avocado, and watercress; gently toss. Pour the vinaigrette over the salad. Toss, and serve.
Soaking the onions in step one makes removing the skins easier to peel.