Preheat oven to 200°C.
Place gravy beef into an oven tray and toss with the cornflour.
Add onion, garlic and bay leaves and drizzle all with EVOO, then roast for 30 minutes.
Cool slightly before transferring to the Thermomix bowl with all other ingredients except salt. Cook 60 min/90°C/speed 1.
Taste the mixture to see how you feel about it. If you feel that it needs more sugar, or vinegar, this would be the point to add it. You need to taste it prior to salt going in as it is inedible by the spoonful once the salt has been added.
Add salt and blend 20 sec/speed 8.
Transfer into hot sterilised jars and cool with lids on. Keep in the fridge and use as directed in recipes or to replace liquid stock at the ratio of approximately 1–2 tablespoons to 500ml water.