Prepare Marinade: In a medium bowl, whisk together olive oil, soy sauce, balsamic vinegar, lemon juice, brown sugar, and Dijon mustard. Add in seasonings to taste, ensuring all ingredients are well combined.

Marinate Veggies: Set aside a quarter of the marinade in a separate bowl. Toss chopped veggies in the remaining marinade and refrigerate for at least 30 minutes.

Marinate Chicken: Cut chicken into cubes and coat with the remaining marinade, letting it sit in the refrigerator for at least 4 hours, or ideally overnight.

Soak Skewers: If using wooden skewers, soak them in water for at least 30 minutes to prevent burning.

Prepare Kabobs: Thread the marinated chicken and veggies onto the skewers, alternating them for a mix of flavors and textures.

Cook: Preheat grill to medium-high heat (about 400°F). Grill kabobs for 8-12 minutes, turning halfway, until chicken reaches an internal temperature of 160°F.

Rest and Serve: Remove kabobs from heat and let them rest for 5-10 minutes before serving. Drizzle reserved marinade over before serving.