Saute the chopped onion in a pan until translucent.
Add the bay leaf, vinegar, and tomato sauce and stir to combine well.
Then add the garlic, basil, parsley, thyme, oregano, rosemary, salt, and pepper and mix until well blended. Cover the saucepan and allow to simmer for 10 minutes over low heat.
Add the zucchini, the red bell pepper, and the sweet potato, and stir well, cover, and simmer for another 5 minutes.
Add the eggplant, tomatoes, and tomato paste and stir again to combine everything together well. Cover the pan and continue to simmer until the vegetables are tender, about 8 more minutes, stirring occasionally.
Once the veggies are tender and cooked, remove the pan from the heat immediately to make sure the vegetables don't overcook and become soggy. Serve your vegan ratatouille over quinoa or pasta.