This ratatouille is a beautiful vegetable stew made from fresh, garden-grown vegetables. Thinly sliced zucchini, tomatoes, and eggplant are roasted until tender, accompanied by a fresh vegetable sauce on the bottom. A sprinkle of melted Parmigiano-Reggiano is added on top for an Italian touch to this iconic French dish.
Slice the vegetables: Use a mandoline slicer or chef knife to slice the yellow squash, zucchini, tomatoes, and eggplant into 1/8-inch-thick pieces. Tip: If the size of vegetables varies, you can cut the bigger slices in half or into quarters.
Salt the vegetables and let them sit: Prepare two large baking pans/cookie sheets with a pinch of salt on the bottom of the pans. Then arrange the vegetables on the pan with another generous pinch of salt over top. Let the vegetables sit with the salt for 30 minutes. Note: This helps tenderize the eggplant and zucchini and removes excess moisture from the vegetables, preventing the dish from getting watery. However, this step can be skipped, and the vegetables can be layered into the dish if you prefer to reduce your prep time.
Roast the red pepper: Place a wired rack over a gas range and roast the pepper directly on the open flame of your range. Rotate every few minutes until the whole pepper is nicely charred. After, place it in a bowl and cover with foil for 10-15 minutes. Then use paper towels to remove most of the charring from the outside, remove the core, and dice the pepper.Note: if you don't have a gas range, you can do this with a dry cast-iron pan on the stovetop, or on a grill, or skip this step and add the bell pepper with the tomatoes to the sauce. You can also substitute with jarred roasted pepper to make it easier!
Make the sauce: In a large pan or Dutch oven pot, add the olive oil and saute the diced onions, celery, and carrot with a pinch of salt until soft (about 3 minutes). Then add the pressed garlic and cook for another minute. Then add the diced tomatoes, the diced fire-roasted bell pepper, 1/4 teaspoon garlic powder, 1/8 teaspoon red pepper flakes, 1/4 teaspoon black pepper, and a generous pinch of salt. Let the vegetables cook for about 8 minutes on a medium heat, stirring often. Then add 1 teaspoon of fresh thyme and a splash of red wine and let the wine cook for an additional 2-3 minutes. Then add in torn fresh basil leaves.
Blend the sauce ingredients: Carefully transfer the cooked sauce ingredients to a blender, and blend on high for 30 seconds until the consistency is creamy and smooth. Taste the sauce and adjust with additional salt and pepper if needed.
Prepare the ratatouille: Use paper towels to pat the salted vegetables dry.In a casserole dish (I used a 3.5-quart braiser), spread the sauce on the bottom. Then arrange the sliced squash, zucchini, tomatoes, and eggplants in a circular pattern in the dish, using up all the ingredients that you can fit. Note: I like to alternate between the different vegetables, but you might run out of some before the others, so you can double up on what you have the most of.
Bake: Cover the dish with a lid or tightly with foil, and bake at 375F for 45 minutes. Then remove the lid/foil, sprinkle 1/2 cup freshly grated Parmigiano-Reggiano on top of the ratatouille, and broil on high for 1-2 minutes, or until the cheese is melted and browned. Let cool for several minutes before serving!