You can make this soup with any combination of fresh vegetables on hand. Just be sure to include some potatoes or carrots. Leave the vegetables chunky for a robust soup, or puree half of the vegetables for extra body.
In a large saucepan, heat the oil over medium heat. Add the onion. Saute until it begins to soften, 3-5 minutes. Add all the vegetables, the stock, and herbs. Bring to a boil. Reduce the heat to medium-low and simmer until the vegetables are tender, 15-20 minutes.
Discard the bay leaf. Season to taste with salt and pepper. Ladle into bowls and serve.