For the caramelised onion butter, heat a small saucepan over low heat and add about 1 tablespoon of butter. Add the onion and garlic and cook, stirring regularly for about 10 minutes, then add the vinegar and season with salt and pepper, then continue cooking for another 10-15 minutes until the onion is golden brown and jammy.

Allow to cool to room temperature. Stir through the remaining butter and add the parsley. Hold at room temperature if using straight away, or mould into a log using cling wrap and refrigerate or freeze until ready to use. Heat a frying pan or barbecue until very hot and season the lamb well with salt and pepper. Add the olive oil, then cook the lamb for a few minutes on each side until medium-rare. Rest for 5 minutes, then return the lamb to the pan or barbecue for just 30 seconds more on each side to bring the outside to heat. Add about a tablespoon of softened butter to the top of each lamb steak to serve.

Serve with Adam Liaw's honey-roasted carrots.