Heat the oil in a pan and add the vegetables and bay leaf. Stir in the sugar with some salt. Gently cook for 10-15 mins until the veg is tender.
Stir in the tomatoes and 150ml water. Simmer very gently for 30 mins until the sauce has reduced by two-thirds and is very thick. (If you have doubled or tripled the quantities, this may take up to 1 hr.)
Stir occasionally, particularly towards the end of the cooking time, so that the sauce doesn’t catch on the bottom.
If you like your sauce a little thinner, add a splash of water.
Serve half with gluten free pasta and chill or freeze other half in 1-2 batches for later use.