Heat a large cast iron casserole dish to a medium high heat with a dash of EVOO. Season the steak with salt and pepper. Brown the steak slightly then take off heat. Preheat the oven to 150°C.
Place onion, garlic, chilli and remaining EVOO into the Thermomix bowl. Chop 4 sec/speed 5. Sauté 5 min/Varoma/speed 1.
Add wine, soy sauce, sugar and a little of the basil and combine with spatula. Pour over steak and stir to combine.
Place into the oven, covered for up to 4 hours. Check the consistency of the meat at 3 hours and either add heat or remove from the oven and proceed. This depends entirely on your oven and its accuracy.
Carefully pour into clean Thermomix bowl and "pull" 4 sec/Reverse/speed 4. This is best done in batches of half a TM bowl at a time.