Ingredients:

  • 450 g (16 oz) Ribeye or Sirloin steak (1.5 in thick, room temperature)
  • 10 g (2 tsp) Coarse Sea Salt
  • 5 g (1 tsp) Freshly Cracked Black Pepper
  • 30 ml (2 tbsp) Neutral Oil (Grapeseed)
  • 40 g (3 tbsp) Unsalted Butter
  • 2 sprigs Fresh Thyme or Rosemary
  • 2 cloves Garlic, smashed and unpeeled
  • 300 g (2 large) Yellow or Sweet Onions, sliced thinly
  • 15 ml (1 tbsp) Olive Oil
  • 5 ml (1 tsp) Balsamic Vinegar (optional)
  • 60 ml (1/4 cup) Full-fat Mayonnaise
  • 10 ml (2 tsp) Dijon Mustard
  • 2 g (1/2 tsp) Garlic Powder or Finely Minced Garlic
  • 5 ml (1 tsp) Freshly squeezed Lemon Juice
  • 2 portions Crusty Bread (Ciabatta or Baguette), halved lengthwise
  • 60 g (2 oz) Provolone or Gruyère Cheese, sliced (optional)
  • 30 g (1 cup) Arugula or Watercress

Instructions:

  1. Prepare the Onions: Slice onions thinly. Heat olive oil in a skillet over medium-low heat. Add onions and a pinch of salt. Cook slowly, stirring every 5-7 minutes, until deeply mahogany brown and sweet (20–25 minutes). Stir in balsamic vinegar, if using, and set aside.
  2. Make the Aioli: In a small bowl, whisk together the mayonnaise, Dijon mustard, garlic powder (or fresh minced garlic), and lemon juice. Season lightly with salt and pepper. Chill until ready to assemble.
  3. Season the Steak & Preheat: Pat the steak completely dry with paper towels. Season aggressively on all sides with salt and pepper. Preheat the cast iron pan over high heat until smoking hot.
  4. Sear the Steak: Add neutral oil to the hot pan. Carefully place the steak in the pan. Sear for 3 minutes without moving it to form a deep crust. Flip.
  5. Baste and Finish: Reduce heat to medium. Add butter, thyme/rosemary, and smashed garlic to the pan. Tilt the pan and use a spoon to continuously baste the melted, foamy butter over the steak for 1-2 minutes until internal temperature reaches 52°C (125°F) for rare, or 57°C (135°F) for medium-rare.
  6. Rest and Slice: Immediately transfer the steak to a cutting board. Rest for a minimum of 8–10 minutes. After resting, slice the steak thinly against the grain.
  7. Toast the Bread: While the steak rests, lightly spread the interior of the bread rolls with butter or olive oil. Toast under a broiler or in a clean skillet until golden brown. If using cheese, place the cheese slices on the top half of the toasted bread and return to the broiler until melted and bubbly.
  8. Assemble: Spread a generous layer of Dijon-Garlic Aioli on both sides of the toasted bread. Layer the base with a handful of fresh arugula, followed by the thin slices of rested steak, and top with the warm caramelized onions. Close the sandwich and serve immediately.