A good tomato pasta base is essential for dishes such as pizza, pasta or parmigiana. If you have an abundance of tomatoes it freezes well.
In a large frying pan over medium heat, cook the onion in olive oil until translucent. Stir in tomatoes, cook until juice begins to thicken.
Stir in tomato purée, salt and pepper. Reduce heat and simmer 15 minutes more, until rich and thick.