Prepare the marinade by whisking together balsamic vinegar, honey, soy sauce, garlic, salt, and black pepper in a bowl.
Split the marinade into two bowls, reserving half for later as a glaze.
Add the beef cubes to one bowl and the chicken cubes to the other, making sure each piece is well-coated.
While the meats marinate, soak the wooden skewers in water for 30 minutes to prevent them from burning.
Preheat the grill to medium-high heat, about 400°F (200°C).
Thread the marinated beef and chicken onto the soaked skewers, alternating with pieces of vegetables.
Grill the skewers for approximately 10-15 minutes, turning occasionally, until the meats are cooked through.
During the last few minutes of cooking, brush the reserved marinade over the skewers for a flavorful glaze.
Remove the skewers from the grill and let them rest for a few minutes before serving.
Serve the skewers warm, drizzled with more balsamic glaze if desired, alongside your favorite sides.
