If you use fresh tomatoes to make low carb pasta sauce, they will have to be blanched first to get the skins off, then chopped up, and cook them down until they reach the desired texture. Plum tomatoes are too dry and will not give you the consistency that you need.
Rao's Arrabbiata Sauce: Rao's sauce is the critical ingredient in this keto tomato soup. We prefer arrabbiata sauce since it has more flavor (and heat) than regular marinara sauce.
You can also use fresh tomatoes but you will have to blanch them first to remove the skins. If you want your keto pasta sauce to be smoother, and are using fresh tomatoes that have not been cooked down, then you could blend it with an immersion blender or in a traditional blender.
Our recipe uses a can of crushed, pureed or plum tomatoes but choose the one with no added sugar (check the ingredient label when buying). It all goes in a blender with a little olive oil and your favorite spices.