Place a stockpot or pasta-size pot over medium heat. Add a generous lug of olive oil and add the onion, celery and garlic. As soon as you hear a sizzle, turn heat to low and let them sweat for 10 minutes or until translucent.
Add the thyme and cook for another minute or so, then add the tomatoes, wine and stock. Give it a good stir then add the brown sugar and vinegar. Cover with a lid and simmer for 4 hours, checking on it and giving it a stir every hour or so. (Note: cover with a lid for at least half of the cooking time. To speed up the rate of reduction, remove the lid after two hours, for all or part of the remaining cooking time.)
Taste and adjust seasoning accordingly. Stir through the miso, if using, and cook for another 30 minutes, until the mixture intensifies in colour and consistency.
Depending on how broken down your vegetables are, use a stick blender and give it a quick whiz to break down any larger chunks. Store in an airtight container in the fridge or freezer.
Makes about 5 cups (after 4 hours' cooking time; quantity will reduce if left on stove longer).
