For this sauce, you can choose to remove the skin from the tomatoes or to leave it on. I prefer removing the skins as that way I get a smoother sauce.
If you are going to remove the skin: make an x in the bottom of the tomatoes with a knife and put them into a pot with boiling water for half a minute. Fish them out of the water with a spatula and put them into a bowl with cold water immediately. After that, you can easily remove the skins.
Cut the tomatoes into small cubes and put them in a pan with some garlic-infused olive oil. Let them cook over low heat until they start to soften. Then add the tomato passata, salt, pepper, Italian herbs mix and 1 tablespoon of red wine vinegar and let it simmer over medium heat for about 10 minutes.
You can serve it as it is or if you want a smoother consistency you can blend it.
If the tomatoes that you are using are too sour you can add 1 or 2 tablespoons of maple syrup or sugar(according to taste).