For the vinaigrette: Combine the vinegar, honey, mustard and garlic in a large bowl. While whisking, drizzle in the olive oil so it lightly emulsifies. Season with salt and pepper and set aside.
For the couscous: Heat the chicken broth in a pot over medium-high heat. Set another large pot over high heat and add the couscous. Allow the couscous to brown while you toss and stir it, about 5 minutes. When it is done it will be lightly browned and fragrant. Season the couscous with salt. Add the heated chicken broth to the couscous and shut off the heat. Cover and allow to stand for 5 to 7 minutes. Remove the lid and fluff the couscous with a fork.
Add the chopped vegetables to the vinaigrette and toss to coat everything evenly. Fold in the couscous and serve.