To make pizza sauce from scratch first you need to cook tomatoes.
In a pan add 2 cans of whole peeled tomatoes. Squish the tomatoes with your hands or crush them using a masher. Do not blend them completely because we need very small chunks to concentrate the flavour.
Add a splash of olive oil, dried rosemary, roasted red chilli flakes and stir it.
Cover with a lid and allow the pizza sauce to simmer for 20 minutes or so.
Stir it once or twice in between.
Now tear some fresh basil with hands and add. Also add sea salt or kosher salt and a teaspoon of sugar.
Simmer for few more minutes and you best, rich, flavourful homemade pizza sauce from scratch is ready.
You can make it as thick as you want. That means longer you simmer it thicker and concentrated it becomes.
When it is done taste to adjust seasonings and flavour as per your taste preference.