Firstly, pickle the onions. Simply mix the onion and vinegar in a small glass bowl. Setaside for 5 - 10 minutes or until the onion softens slightly.
Rub the steaks with garlic oil and season with sea salt and black pepper.
Heat and chargrill over medium-high heat.
Cook the steaks on each side for 2 - 3 minutes or until cooked to your liking. Transfer to a plate. Cover with foil and set aside to rest before slicing.
Place a slice of toasted bread on each serving plate and spread it with hummus. Layer with salad leaves, sliced tomato, and pickled onion and top with sliced steak.
Sprinkle with grated fresh parmesan before serving.