Heat the oil in a large non-stick frying pan and gently cook off the onion, leek, celery and carrots for 20 minutes or until softened
Add the peppers and cook for a further 10 minutes before adding the garlic, tomatoes, vinegar and sweetener
I like to pulse all my veggies in my food processor to cut the time taken for the first couple of steps. If using a food processor you can get away with not using any oil and you can throw everything in together and go straight to the simmering in step 4
Simmer gently, covered for 40 minutes then take off the heat and let cool
Puree smooth in a blender. If your kids don't mind specks in their sauce, add a handful of fresh basil to the blender. The dried herbs won't be so obvious but you can leave them out if you like. The sauce can be divided into portions and frozen for use at a later date. A quick idea is to cook 300g dry pasta off then drain and add into the reheated sauce. That will serve 4 adults using half of the sauce. Maybe serve topped with some parmesan-style cheese, or use as a bolognese base or lasagne sauce
If you can't use tomatoes use the same weight of my Tomato-Free Tomato Sauce recipe instead
