1. Heat the olive oil in a large, heavy-bottomed pot over medium-high heat. Add the onion with a pinch of salt and cook, stirring often, until softened, about 5 minutes.
2. Stir in the garlic and cook until aromatic, about 30 seconds. Add the eggplant, zucchini, squash, and bell pepper. Season well with salt and pepper.
3. Cook, stirring occasionally and being careful not to let anything stick to or brown on the bottom of the pot, until the vegetables are halfway tender, about 7 minutes.
4. Add the tomato and thyme, mix well, and bring to a simmer. Cook until thickened. Remove from the heat and stir in the basil. Adjust the seasoning and set aside to cool.
Recipe provided by James Briscione, chef instructor at the Institute of Culinary Education.