Place garlic, onion, carrot, celery and oil into Thermomix bowl and chop 3 sec/speed 5. Sauté 10 min/Varoma/speed 2.
Add remaining ingredients to Thermomix bowl and cook 60 min/80°C/speed 2.
To reduce further for a thicker sauce, cook 30 min/100°C/speed 2 using the spatter guard or the simmering basket in place of the MC. If you are happy with the consistency of your sauce, you can omit this 30 minutes.
With MC in place, blend carefully 20 sec/speed 10, bringing speed up slowly.
Use as directed in recipes of choice.