With the rack in the middle position, preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper.
In a pot over medium heat, cook the onions, garlic, eggplant and bell pepper in 1/4 cup (60 ml) of oil until the eggplant begins to brown. Add the remaining vegetables, herbs and chickpeas. Cover and simmer for 15 minutes, stirring occasionally. Season with salt and pepper. Strain the ratatouille, keeping the cooking juices separately.
Meanwhile, place the fish on the prepared baking sheet. Season with salt and pepper. Bake for 10 to 12 minutes, depending on the thickness of the fish.
Place the ratatouille in the centre of four plates. Top with the fish and drizzle with the reserved ratatouille cooking juices. Drizzle droplets of the remaining oil over the cooking juices. Garnish with the thyme.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.