In a large pot, heat a thin layer of olive oil and saute the diced onions until they are reduced and softened.
2-4 tbsp extra virgin olive oil, 1 large red onion
Add the diced pepper and saute for another few minutes until they are also reduced and softened.
1 sweet pepper or bell pepper
Add the garlic and mix through until the fragrance starts to pop, then add the herbs and chili flakes (if using) and mix them through. Don't linger here - once it's all mixed together, move on to the next step because we don't want the garlic or herbs to burn!
6 cloves garlic, 1 Tablespoon dried Italian herbs, pinch red pepper or chili flakes
Add the mushrooms and mix through, then very quickly add in the Worcestershire sauce and balsamic vinegar. Mix through - if the pan seems too dry, add a little more oil or a dash of wine to help loosen it back up, but the mushrooms will soon start to release their liquid and cook down.
5 oz mushrooms, 1 Tablespoon balsamic vinegar, 1 Tablespoon worcester sauce
Allow the vegetables to cook over a low heat until they are well reduced and somewhat caramelized. Then remove them from the heat while you prep the tomatoes
In a large bowl or pot, place as many tomatoes as you can fit in one layer. Cut an X shape through the skins. Pour boiling water over the top and let them soak. (This works best if you have an electric kettle - if you don't, you will find it easier to bring the pot of water to boil and then add the tomatoes in)
4.5 lbs large tomatoes
Allow the tomatoes to soak just for a minute or two. Remove from the water and you should find the skins peel away very easily from the spot where you sliced them.
Peel the skin from the tomato, remove the stem and then slice it into halves or quarters. Remove the most obvious seeds - usually the slightly jelly-like membranes come out easily, but don't go overboard trying to get them all out.
Add the tomato straight into the pot with the vegetables. You can tear the tomatoes or crush them a little with your hands as you add them in to break them up (but they'll cook down on their own eventually so you don't have to.)
Once you've added a couple of tomatoes, put the pan back onto a low heat and let it simmer while you work your way through the the whole batch of tomatoes.
Repeat until all of the tomatoes are in the pot, then add the brown sugar and give it all a good stir.
1 Tablespoon brown sugar
Allow to simmer for 1.5-3 hours (maybe longer if you're not using plum tomatoes). Leave the lid slightly ajar to allow liquid to escape. Stir regularly and check the texture - if the tomatoes are too chunky, you can use a potato masher to break them up and get the texture more homogenous.
Once the sauce has reduced to your liking, you're done! Add the chopped basil through and serve.
1 bunch fresh basil