Steak Sandwich with Sweet & Sour Onions Recipe

Ingredients

• 1 Tbsp. coriander seeds
• 1 Tbsp. mustard seeds
• ½ cup jarred pimentos, drained
• ¼ cup cider vinegar
• ¼ cup Madeira
• ¼ cup sugar
• 1 ½ cups sliced sweet onion (such as Maui or Walla Walla)
• 1 ½ cups sliced red onion
• 1 Tbsp. minced fresh chives
• ½ tsp. kosher salt
• Black pepper to taste
• 1 tsp. kosher salt
• ½ tsp. black pepper
• 2 tri-tip or flat iron steaks, cut in half crosswise (8 oz. each )
• 8 slices ciabatta