How to Make It
Preheat the oven to 400°. Heat the olive oil in a large nonstick skillet. Add the onion and cook over moderate heat, stirring, until translucent, about 3 minutes. Add the red and yellow bell peppers and cook until just tender, about 3 minutes. Add the zucchini and eggplant and cook until just tender, about 4 minutes. Add the tomatoes, garlic, basil and thyme, season with salt and black pepper and toss to combine. Spread the mixture in a medium baking dish and roast for about 10 minutes, or until softened and beginning to brown. Transfer to a plate to cool. Lower the oven temperature to 375°.
Lay the tortillas out on a work surface. Spread half of the ratatouille on the tortillas, leaving a 1/2 -inch border around the edges. Roll up the tortillas and secure each one with a toothpick. Set them, seam sides down, on a baking sheet and bake for about 10 minutes, or until crisp, lightly golden and heated through.
Slice off the ends of each roll and remove the toothpicks. Cut each roll in half diagonally and set 2 halves upright on each of 4 plates. Spoon the remaining ratatouille around the taco towers, garnish with a spoonful of pesto and serve.