Preheat the oven to 400°F.
In a large bowl, toss the eggplant, zucchini, red bell pepper, yellow bell pepper, red onion, garlic, olive oil, balsamic vinegar, salt, and pepper. Spread the vegetables out in a single layer on a baking sheet.
Roast the vegetables in the oven for 25-30 minutes, or until tender and lightly browned.
Remove the vegetables from the oven and cool to room temperature.
Once the vegetables have cooled, transfer them to a large bowl and toss with the chopped parsley and basil.
Serve the ratatouille salad as a side dish or a light lunch.