HOW TO MAKE IT
Heat your charcoal barbecue for at least 15–30 minutes before you start to cook. You want the grill to be sizzling hot.
Place the onion rings in a Dutch oven and arrange the thyme sprigs around the side. Pour the wine over the top, then put the lid on and place over low heat (by this I mean an area of the grill that doesn’t have a lot of coal under it). Allow to simmer gently for 20−30 minutes or until the onion is soft and translucent and the red wine has reduced to a runny sauce.
Add the steak to the hot grill, sprinkle with salt and cook until the meat is medium−rare. Depending on the thickness of the steak slices, this should take about 5 minutes. Remove and rest for a few minutes, then serve with the onion and red wine sauce.