Preheat your oven to 200°C (400°F) and line a large rimmed sheet pan with parchment paper or a silicone mat for easy cleanup.
Gather your vegetables and cut them into uniform 1 cm slices or chunks, creating a colorful assortment ready for roasting. Set aside.
In a small bowl, mix the olive oil with the minced garlic, salt, and pepper to create a flavorful oil mixture.
Toss the chopped vegetables in the oil mixture until evenly coated, ensuring every piece gets a good dose of flavor.
Spread the coated vegetables in a single layer across the prepared sheet pan, giving each piece enough space for proper roasting and caramelization.
Slide the tray into the oven and roast for 25 to 30 minutes, shaking the pan or turning the vegetables halfway through to promote even browning and caramelization.
Once the vegetables are tender and edges are golden and slightly charred, remove from the oven and sprinkle with chopped fresh herbs for a burst of brightness.
Finish with a squeeze of lemon or a drizzle of balsamic vinegar if desired, to enhance the flavors and add a touch of acidity.
Serve the sheet pan ratatouille warm, directly from the pan or transferred to a serving platter, and enjoy the tender, caramelized vegetables with their smoky, herbaceous aroma.