Soak the tomatoes in a bowl or pot with hot boiling water for about 5 minutes to loosen the skins.
After soaking, peel the skins off the tomatoes.
Chop the peeled tomatoes into pieces.
In a pan, heat a few tablespoons of olive oil over medium heat and sauté finely chopped onions until they become soft and translucent, about 5 minutes.
Add the chopped tomatoes to the pan with the onions, stirring to combine. Season with a pinch of salt to enhance the flavors.
Let the mixture simmer on medium heat for about 15 - 20 minutes, stirring occasionally, until the tomatoes break down and the sauce thickens to you liking,
If you prefer a smoother sauce, us a hand immersion blender to blend the pieces and transfer the mixture to a blender.
Blend and add a few chopped up basil leaves.
Serve immediately or store for a later use.