Preheat oven to 400 degrees. Line two sheet pans with foil.
Cut peeled eggplant, peeled zucchini and summer squash, tomatoes and peppers into similar sizes (about 1″ dice or chunk) and lay out on the sheet pans (A.K.A. cookie sheets). See ingredient list for more specific cutting directions. Add several garlic cloves (peeled and thinly sliced) to each sheet pan.
Gather all the vegetables into a mound (or mounds if you have a lot) in the middle of the pan and drizzle mounds of vegetables with 1/4 cup olive oil and about 1 to 1 1/2 tsp. salt. Mix the oil and salt into vegetables gently with your hands and then spread veggies out on the sheet into a single layer.
Roast vegetables in preheated oven for 15-20 minutes, use a flat spatula to turn veggies over and roast for another 15-20 minutes.
Meanwhile, heat a large skillet over medium-high heat and coat the bottom with 2 Tbsp olive oil. When the oil is hot, add the onion, crushed red pepper and season with salt, to taste. Sauté until onions are soft, about 5 minutes.
Add the roasted vegetables to the pan along with the vinegar, oregano and thyme. Toss well to coat and add more olive oil, if needed. Taste to check the seasoning and transfer to a platter and serve.