Bring 5 1/2 cups water in medium saucepot to a boil; add 1 teaspoon salt. Stir in rice and simmer, covered, until water is absorbed, 25 to 30 minutes. Remove from heat and let stand, covered, 15 minutes. Transfer to a bowl and let cool slightly. Toss in parsley, roasted peppers, and scallions, for salad.
Whisk together vinegar, sugar, remaining 3/4 teaspoon salt and the pepper in another bowl. Whisk in oil in a slow stream until thickened and emulsified, for vinaigrette. Add to salad and toss to coat. Serve at room temperature. (can be made ahead. Cover and chill up to 2 days).