Season the New York Strip Steak generously with salt and black pepper on both sides. Allow it to rest at room temperature for about 1 hour.

Heat a cast-iron skillet over medium-high heat for about 5 minutes. Sear the steak for 2-3 minutes on each side until medium-rare. Let the steak rest for 5 minutes before slicing.

In the same skillet, lower the heat, add sliced onions, sprinkle with salt, and sauté for 10-15 minutes until caramelized. Add balsamic glaze in the last minute.

Toast the ciabatta in a preheated oven at 400°F for about 5-7 minutes until golden brown.

Spread lemon herb aioli on toasted ciabatta, layer with arugula, sliced steak, and caramelized onions. Drizzle with extra balsamic glaze and serve warm.