Ingredients

  • 3 Cup very thinly sliced sweet onion (about 1 large)
  • 3 Tablespoon olive oil, plus more for oiling grill
  • 2 Teaspoon thyme leaves
  • 1 Tablespoon balsamic vinegar
  • 2 Teaspoon brown sugar
  • salt and pepper
  • 1/3 Cup mayonnaise
  • 1 Tablespoon prepared horseradish
  • 1 Teaspoon lemon juice
  • 2 (8 oz) beef strip loin steaks
  • 4 Slice sourdough bread (8 if making closed sandwiches)
  • 1/4 Cup roasted red pepper, thinly sliced
  • 1/2 Cup arugula or watercress, for garnish, if desired

Method

  • Preparation
  • 1.Preheat a grill or grill pan to medium-high.
  • 2.In a large non-stick skillet set over medium-low heat, add onions, oil and thyme and cook covered, stirring occasionally until soft and translucent, about 10 minutes. Add vinegar and sugar and cook until caramelized, about 4 minutes. Season to taste with salt and pepper and set aside.
  • 3.Meanwhile, combine mayonnaise, horseradish and lemon juice in a bowl and stir to blend. Season to taste with salt and pepper and set aside
  • 4.Season steak with salt and pepper and place on an oiled grill. Cook, turning once until desired doneness is reached, about 3 to 4 minutes per side for medium-rare. Let rest, lightly covered with aluminum foil for 5 minutes before slicing.
  • 5.Toast or grill bread and spread one side of each slice with mayonnaise. Layer with red peppers, onions, steak, and arugula.