Preheat your oven to 200°C (400°F). Line your large sheet pan with parchment paper for easy cleanup.
Prepare all vegetables by slicing zucchini, eggplant, bell peppers, and tomatoes into uniform 1/4-inch slices. If using eggplant, salt the slices and let sit for 15 minutes to draw out bitterness, then rinse and pat dry.
In a large mixing bowl, toss the sliced vegetables with minced garlic, chopped herbs, olive oil, salt, and pepper until evenly coated. Use a silicone spatula or tongs to gently mix and coat everything well.
Spread the coated vegetables in an even layer on the prepared sheet pan, giving each piece space to breathe and caramelize as they roast. Avoid overcrowding for the best texture.
Place the pan in the oven and roast for about 25-30 minutes. After the first 15 minutes, gently toss or turn the vegetables to promote even caramelization and prevent sticking.
Check for doneness: the edges should be darkened and slightly crispy, while the vegetables remain tender and fragrant. The smell of roasted garlic and herbs should fill your kitchen.
Remove the pan from the oven and sprinkle generously with freshly chopped herbs. For an extra touch, squeeze a little lemon juice over the vegetables to brighten the flavors.
Allow the ratatouille to rest for 5 minutes so the flavors can meld. Serve it warm, garnished with more herbs if desired, and enjoy the rustic, caramelized goodness.