Step 1

Garlic Aioli: Mix mayonnaise and garlic together. Set aside for 30 minutes+ for the flavour to develop (do not keep for more than 3 days tops).

Step 2

Caramelised Onion: Melt butter in a skillet over medium low heat. Add onions and stir to coat in butter. Place lid on (or place a baking tray over skillet) and leave for 20 minutes, stirring once or twice. Remove lid then cook for a further 20 minutes, stirring every now and then, until onion is golden (increase heat slightly if the colour is not changing). Add sugar, vinegar, salt and pepper. Cook for a further 10 minutes until jammy. Remove from heat and keep warm.

Step 3

Take beef out of fridge 20 minutes before cooking. Season generously with salt and pepper.

Step 4

Heat oil in a skillet over high heat (or heat BBQ). Cook steak to your liking - if using a secondary cut like Bavette, skirt or flat iron, it's best medium rare.

Step 5

Transfer beef to a plate, cover loosely with foil and rest for 5 - 10 minutes. Then slice thinlyagainst the grain.

Step 6

Cut turkish bread into 15cm/6" lengths and split into half. Toast lightly.

Step 7

Spread the bottom piece generously with garlic aioli. Top with rocket, then tomato slices, beef, caramelised onion. Spread the top piece of bread with mustard then place on top.