Grilled Flank Steak

1. Combine Worcestershire sauce, soy sauce, brown sugar, anchovies, garlic, mustard, tomato paste, and vegetable oil in a blender and blend until smooth, creamy, and emulsified. Transfer 1/3 of marinade to a small container, add chives and shallots, stir to combine, and reserve. Place flank steak inside a gallon-sized zipper-lock bag with remaining marinade. Press out air, seal bag, and allow meat to marinate, turning occasionally, for at least 1 hour and up to 12. 2. Remove steak from marinade and pat dry with paper towels. Light one chimney full of charcoal and wait until they're covered in grey ash. Spread evenly over 1/2 of grate, leaving other half empty. Put cooking grate in place, cover, and allow grill to preheat for 5 minutes. Clean and oil grilling grate, then place flank steak over hot side of grill, cook until well charred, about 3 minutes. Flip steak and continue to cook until second side is well charred, about 3 minutes longer. Transfer steak to cooler side of grill, cover, and cook until center of steak registers 125°F (52°C) on an instant-read thermometer for medium-rare, or 135°F (57°C) for medium. Transfer to a cutting board, tent with foil, and allow steak to rest for at least 5 minutes. Carve and serve, passing extra marinade tableside.