Clean your grill grates and preheat to medium-high heat.
Cut the vegetables and place them in a large mixing bowl. Pour the olive oil over the top and then sprinkle with salt and pepper. Toss gently until the vegetables are coated with oil.
Thread the vegetables onto the skewers so they're just touching. Don't squeeze them together tightly so they will cook more evenly.
Grill the skewers for 4-5 minutes per side, then remove and serve.
Notes
If using wooden skewers, soak them in water for at least 30 minutes to avoid burning.
Store leftovers in an airtight container and refrigerate for up to 5 days.