"This is one of my favorite salads, and is a great way to use leftover chicken! The flavor combination of all the veggies and pop of vinegar makes this couscous salad really stand out. Refrigerating is optional. Bon appetit!"
Bring water and 1 tablespoon olive oil to a boil in a medium pot over high heat. Add couscous; quickly lower heat and let simmer until water is absorbed, 7 to 8 minutes.
Whisk balsamic vinegar, 2 tablespoons olive oil, sugar, salt, and pepper together in a small bowl until dressing is evenly combined.
Fluff couscous with a fork and place in a large, shallow bowl. Add black beans, corn, chicken, and red bell pepper. Fold salad together and pour in the dressing in 3 batches, mixing well after each addition. Refrigerate until chilled, about 30 minutes.