Antipasto Salad

1/2 teaspoon sugar

1/2 teaspoon salt

1/8 teaspoon black pepper

6 tablespoons extra-virgin olive oil

2 cups water

3 tablespoons red-wine vinegar

2 tablespoons sugar

1 teaspoon salt

1 medium red onion, halved lengthwise and thinly sliced crosswise

2 hearts of romaine (12 ounces total), torn into bite-size pieces

1 cup loosely packed fresh flat-leaf parsley leaves

1 (8-oz) jar roasted red peppers, rinsed, drained, and cut lengthwise into 1/4-inch-thick strips

2 (6-oz) jars marinated artichoke hearts, drained

1 cup assorted brine-cured olives

1 cup drained bottled peperoncini (5 ounces)

1/2 lb cherry tomatoes, halved