Sauté Aromatics: Heat olive oil in large pot over medium heat. Cook onion until softened (5 mins). Add garlic, cook 1 minute.
Cook Eggplant: Add eggplant, stir to coat. Cook 10 mins, stirring occasionally.
Add Vegetables: Add zucchini and bell peppers. Cook 5 more minutes.
Add Tomatoes & Herbs: Stir in tomatoes, bay leaf, thyme, salt, and pepper.
Simmer: Bring to gentle simmer, reduce heat to low. Cover partially.
Slow Cook: Simmer 1-1.5 hours, stirring occasionally, until vegetables are tender but intact.
Finish & Serve: Discard bay leaf/thyme stems. Stir in fresh basil. Serve warm, room temp, or cold.