Combine your onion, garlic, parsley, tomato paste, balsamic vinegar, and vegetable oil in a food processor. Blend until smooth to create a rich, flavorful marinade. I recommend tasting it before adding to the chicken. You can always tweak the balance of flavors with more salt, pepper, or vinegar to suit your taste.

Cut the chicken into bite-sized cubes and place them in a medium bowl. Season with salt and pepper, then pour the marinade over the chicken. Use your hands or a spoon to coat each piece thoroughly. Cover and refrigerate for at least 1 hour. If time allows, marinate the chicken overnight for even more intense, developed flavors.

Remove the chicken from the fridge and thread the marinated cubes onto skewers, leaving a little space between each piece for even cooking. If you’re including vegetables, I recommend skewering them separately to ensure they cook perfectly without undercooking or overcooking the chicken.

Preheat your grill to medium-high heat (or your oven to 425°F). Lightly coat the grates or baking sheet with oil to minimize sticking. Place the skewers on the grill and cook for about 5–7 minutes per side, turning occasionally for an even char. If roasting, bake for 15 minutes, then broil for an additional 2–3 minutes to achieve a golden finish. Always check for an internal temperature of 165°F to ensure the chicken is fully cooked.