Open-Faced Steak Sandwiches Recipe

Ingredients

• ½ cup cider vinegar
• 1 Tbsp. sugar
• 1 Tbsp. kosher salt
• 1 cup thinly sliced red onions
• ¼ cup sour cream
• 1 Tbsp. prepared horseradish
• 1 Tbsp. chopped fresh rosemary
• 1 tsp. fresh lemon juice
• 1 tsp. Worcestershire sauce
• Tabasco sauce, kosher salt, and black pepper to taste
• 1 ½ lb. flank steak
• 2 Tbsp. olive oil, divided
• 6 slices baguette (bias-sliced ½-inch thick)
• 1 ½ cups baby arugula