Sprinkle in your oil.
Dice the onion.
The onion does not have to be diced perfectly, since it will be blended anyways. Add in your garlic. Sautee till onion is transparent.
It should look somewhat like this by now.
Add in your balsamic. Before adding vinegar, you can choose to add tomato paste. Just make sure to cook until the paste darkens, then add the vinegar.
Add in 3 cups of water.
Dice tomatoes. Tomatoes do not have to be diced perfectly; they will be blended later on anyways.
Your soup should look like this by now.
Bring soup to a boil. Then, cover pan and simmer at medium-high heat for about 15 minutes.
Add in salt according to your taste preferences.
Pour mixture into blender. Blend until your soup is as smooth as you would like it to be.
Garnish with basil if you would like to.
Enjoy your soup with grilled cheese sandwiches! 🍞