1. Cook corn in boiling salted water in a large stockpot 3 to 4 minutes; drain. Plunge corn into ice water to stop the cooking process; drain. Cut kernels from cobs.
2. Whisk together 1/4 cup sugar and next 4 ingredients in a large bowl; add corn, onion, bell pepper, and parsley, tossing to coat. Cover and chill at least 2 hours.