Finely dice onion, garlic and celery stalk.
Heat 1 tablespoon of olive oil in a large saucepan or soup pot over medium heat.
Add diced onion, garlic and celery and sauté until onions are soft and translucent, about 3-5 minutes.
Add crushed tomatoes, zucchini (or carrot), Italian herbs, tomato paste, maple syrup, vegetable broth and salt (the amount will depend on how salted your veggie stock is).
Bring to boil and let simmer covered with a lid while occasionally stirring for about 15-minutes until celery and zucchini are soft.
Puree the soup using a (high-speed) blender or an immersion blender. Make sure to let the soup cool for a couple of minutes before transferring it to a blender. (see notes)
Return the soup back to the pot. Season to taste.
Feel free to add some coconut milk or heavy cream or vegan alternative to achieve an even creamier texture!
Add more veggie broth if you desire a thinner consistency.