Preheat your oven to 425°F (220°C).
Wash all the vegetables thoroughly. Cut the zucchini into half-moon slices, the bell peppers into strips, the cherry tomatoes in half, and the red onion into wedges.
In a large mixing bowl, combine all the prepared vegetables.
Drizzle the olive oil over the vegetables and sprinkle in the garlic powder, dried oregano, salt, and black pepper. Toss everything together until the vegetables are evenly coated.
Spread the seasoned vegetables in a single layer on the sheet pan.
Place the sheet pan into the preheated oven and roast for 25 minutes, stirring halfway through, until the vegetables are tender and slightly caramelized.
Remove the sheet pan from the oven and let it cool for a couple of minutes before serving.
Feel free to customize this recipe by adding your favorite vegetables or herbs.
Store any leftover veggies in an airtight container in the fridge for up to 3 days. They are great in salads or wraps.