Cut the pork tenderloin into 1-inch cubes. In a medium-size bowl, add the zucchini, yellow squash, red bell pepper, and red onion.
Add the olive oil, dried herbs, salt, and pepper, and toss until coated.
Thread the pork cubes on water-soaked skewers along with the zucchini, yellow squash, red pepper, and onion. Grill for 8 to 10 minutes until the meat is cooked all the way through (should reach an internal temperature of 145°F). Remove from the grill and serve warm.