Heat oil in a large pot over medium-high heat. Add the onion, carrots, and celery. Cook until slightly softened, stirring occasionally.
Add the garlic and saute until fragrant.
Pour in the broth and add the tomatoes. Bring to a boil.
Add the cabbage. Reduce the heat, cover, and simmer for about 30 minutes or until the cabbage is tender. Stir occasionally.
Stir in the salt, oregano, basil, and lemon juice. Cook for another 5 minutes, and you're done!
Notes
Green cabbage's mild sweetness and tender texture make it the best choice for this vegan soup recipe. Napa cabbage might get too mushy, while red cabbage has a bolder flavor than green cabbage.
For cabbage soup leftovers, transfer them to an airtight container and refrigerate for up to 5 days. You can also freeze the cooled soup for up to 3 months. To serve, thaw in the fridge overnight and reheat over medium heat on the stove.