Cut, peel, and dice the onion. I like to use a chopper because it makes all of the pieces the same size. Then, add the olive oil to a hot pot. After that, add the onions to the pot and sauté them. Next, add some salt and continue to sauté the onions. The onions will be done cooking when they are translucent. 

Peel and crush two to three cloves of garlic depending on the size. If you don’t have fresh garlic, pre-crushed garlic will work. Make sure to add the garlic after the onions are cooked because garlic burns quickly. Next, crush the dried oregano in your hand as you add it to the pot. Then, combine all of the ingredients in the pot.

After that, it’s time to add the San Marzano tomatoes. San Marzano tomatoes are perfect for this recipe because they have less acid than regular tomatoes and make a superb marinara sauce. They come whole so make sure to squish them with your hand before adding them to the pot. Keep in mind that if you squish them by hand, it may get messy, so put a towel over the bowl. Another option is to use an immersion blender or blender for the tomatoes. Blend the tomatoes until the desired consistency. 

Then, pour the tomatoes into the pot with the onions. Also, you can always blend the onions if you want the sauce super smooth. At this point, taste the marinara sauce and add any extra salt to taste. After that, add the basil and let the soup simmer for 15-30 minutes to allow all of the flavors to combine. Enjoy!