Pan-Seared Steak with Mustard Seeds, Black Pepper, and Rosemary | Christopher Kimball’s Milk Street

Ingredients

• 1 tablespoon yellow mustard seeds
• 1½ teaspoons black peppercorns
• 1 tablespoon fresh rosemary
• Kosher salt and ground black pepper
• 2 1-pound beef sirloin strip steaks, trimmed
• 2 tablespoons neutral oil
• 3 tablespoons salted butter, cut into 1-tablespoon pieces, divided
• 1 medium shallot, finely chopped
• 2 tablespoons whole-grain dijon mustard