How to Make Tomato Puree
To make a basic tomato puree, place 2 pounds of fresh tomatoes in a large pot of boiling water for 10-15 minutes. Transfer the tomatoes to a bowl of cold water for about 5 minutes or until the skins begin to split. Remove the tomatoes from the water and peel off the skins, then puree the tomatoes in a food processor. Transfer the puree to a sauce pot and simmer it with vinegar, sugar, and salt for 30 minutes to 1 hour. Store the tomato puree in airtight containers.
Gather fresh tomatoes. Any variety will work. Plum tomatoes are commonly used for tomato purees. Remove any leaves and stems from the tomatoes and rinse off dirt. Cut the stem area off the top of the tomato, then cross-cut a slit into the bottom of the tomato. This promotes even cooking and makes it easier to peel the tomato skins off later. Boil a large pot of water.  Add the tomatoes and cook for 5-15 minutes.  Remove the tomatoes from the boiling water and put them into a pot of cold water. Leave them in the cold water for 5 minutes or until the skins begin to split. This is called blanching and loosens the skin for easy peeling. Peel the skins off the tomatoes if you do not want them in your puree and discard. Some people leave the skins on and allow them to be pureed. Cut the tomatoes in half. Remove the seeds and juice if you do not want those parts. This is optional. Puree the tomatoes in a food processor. If you have removed the juice and seeds, you will have a thicker puree and it will be a darker red color. Boil the pureed tomatoes with 1/2 cup of vinegar, 1/2 cup of sugar (optional) and 1 tablespoon of salt per 2 lbs. (1 Kg) of fresh tomatoes. This entire step is optional, but will allow the tomato puree to keep longer. Some cooks prefer to use the pure tomato puree and not add the other ingredients. You can also add sauteed onions and/or green peppers to cook with the tomato puree. Simmer the puree until you have the desired consistency. This time can vary depending on the type of tomato you are using. The time frame can range from 30 minutes to 1 hour. Remove the lid after the first 20 minutes to allow the puree to cool down. Store your homemade tomato puree in small-to- medium-sized containers. If you are planning on storing the puree for a long period, be sure to follow proper preserving guidelines, such as creating a proper acidic balance, reheating to a boil before storage and using clean storage jars to avoid bacteria growth. Another way to store the puree is to freeze it in an ice cube tray and store the frozen puree cubes in a bag in your freezer. This takes up less space and allows you to access varying amounts of puree as needed. Add the butter to a frying pan or skillet. Add the onion and celery. Cook until translucent. Add the tomatoes.  Pour in the stock. Bring to the boil. Reduce to a simmer. Continue simmering until the base softens. Remove from the heat. Allow to cool a little, then blend. Add the seasoning before blending. Blend to the desired consistency. Serve. Add chopped parsley before using or serving. 
Gather fresh tomatoes. Remove any leaves and stems from the tomatoes and rinse off dirt. Boil a large pot of water. Add the tomatoes and cook for 5-15 minutes. Remove the tomatoes from the boiling water and put them into a pot of cold water. Peel the skins off the tomatoes if you do not want them in your puree and discard. Cut the tomatoes in half. Puree the tomatoes in a food processor. Boil the pureed tomatoes with 1/2 cup of vinegar, 1/2 cup of sugar (optional) and 1 tablespoon of salt per 2 lbs. Store your homemade tomato puree in small-to- medium-sized containers. Add the butter to a frying pan or skillet. Add the tomatoes. Pour in the stock. Remove from the heat. Serve. 