First, we make the tomato stew base. Finely chop the onion and carrot, and mince the garlic.
Cook the onion and carrot in olive oil over medium heat until soft and the onions are just beginning to brown. Add the garlic and generously season with salt and pepper. Cook for another minute.
Then add the tomato sauce and stir together. Turn off the heat and set aside until you need it.
Next, chop up the eggplant, green zucchini, yellow zucchini and tomatoes. The goal here is to cut the pieces into half moon, or half coin shapes and for all the pieces to be relatively uniform in size. It’s OK if the tomato slices are a little thicker, as they will cook faster, but keep the eggplant, zucchini and squash pieces on the thin side.
In an 8×8 square casserole pan, add the tomato stew. Then layer the sliced vegetable pieces over the top. You want the pieces to be at least half submerged in the stew.
Cover the pan in aluminum foil and bake in the oven at 375°F for 45 minutes. During the last 10 minutes of baking remove the foil.
Top with chopped parsley and serve warm.
Notes
You can chop vegetables by hand or use a mandoline for keeping them uniform in thickness.Since the vegetables are the star of this recipe, aim for the most fresh and in season ones you can find—it really will make a differenceYou can make this a day ahead by following the recipe up to the point of baking and instead cover the dish in aluminum foil and refrigerate until you are ready to bake.I don’t think ratatouille makes great leftovers. This is just my opinion. But if you do have leftovers, here is what I recommend. Place everything in a blender and puree, you can leave it with some vegetable chunks or puree until smooth. You can store this in the fridge for at least 3 days. Rewarm in the microwave or on the stovetop and serve as soup.