Ingredients:
3.6 kg tomatoes
20 g olive oil
Instructions:
Rinse the tomatoes well, remove the stems, and cut into chunks.
Fill a blender jar with the tomato chunks and blend until the tomatoes have all reduced to a fine sauce.
To strain out the seeds and skin, place a mesh strainer or food mill over a large pot on the stove (or over the crock of a slow cooker pot). Pour the tomato sauce into the strainer. Use a spoon or a spatula to press the tomato sauce through the strainer into the pot below.
Repeat with the remaining tomatoes. If you want to add red peppers or other vegetables, now is the time to do it.
Cook the tomato sauce in the slow cooker on low with the lid off. In the slow cooker, you can leave the tomato paste unattended for longer periods of time. Still, as it starts to thicken, you will also need to check on it more often to prevent it from burning.
Yield: Makes about 510 g.
Storage
It can be stored in the fridge for 7-10 days or even longer if the paste was reduced enough.
It can also be canned or frozen. (Add some citric acid (which can be in the form of a bit of lemon juice) to the paste before canning. If it’s concentrated enough, it may not need it.)
Freezing in perfectly in square ice cube trays, is a great way to save space in the freezer. (The cubes can be stored in freezer bags.)
Borrowed from: https://thethingswellmake.com/easy-homemade-tomato-paste-recipe/