Allow steaks to come to room temperature for about 30 minutes, then season with salt and pepper.

Halve the garlic bulb, drizzle with olive oil, wrap in foil, and place on the grill to roast.

Preheat grill and cook steaks for 3-4 minutes per side for medium-rare; let rest for a few minutes.

Brush ciabattas with olive oil and grill for 2-3 minutes until toasted.

In a pan, sauté sliced onions in butter, add brown sugar and balsamic vinegar, and cook until caramelised.

Blend egg yolk and mustard, then gradually add olive oil for the aioli; mix in roasted garlic, chives, and lemon juice.

Slice rested steaks against the grain into thin strips.

Assemble the sandwich with aioli, steak, caramelised onions, and fresh rocket.