Peel and finely dice the red onion.
Peel and finely dice the carrot and celery.
Peel and crush the garlic cloves.
Heat saucepan on medium heat, add oil and diced onion and cook until softened. Add garlic and stir for 2 minutes.
Add the diced carrot, celery, rosemary and thyme. Stir together and cook for around 7 minutes, stirring regularly to avoid sticking to the pan. Once the vegetables have softened, add red wine and cook until most of the liquid has evaporated.
Add the vegetable stock and gently simmer for around 10 minutes.
Strain liquid into a bowl, taking care to reserve the liquid which will form the stock of the gravy base. Pour liquid back into the saucepan and put back on medium heat.
Make a slurry from the corn flour and water, ensuring there are no lumps. Add corn flour slurry to the pan while whisking until the gravy thickens. Add tomato paste, vegemite, mustard, sugar, salt and pepper. Stir until well mixed.