2 tablespoons Dijon mustard 2 tablespoons tomato paste ½ cup vegetable oil 2 tablespoons chopped fresh chives 1 medium shallot, minced (about 2 tablespoons) 1 flank steak (about 2 pounds) To make the marinade: Combine the Worcestershire sauce, soy sauce, brown sugar, anchovies, Marmite, if using, garlic, mustard, tomato paste, and vegetable oil in a blender and blend until smooth, creamy, and emulsified Transfer one-third of the marinade to a small bowl, add the chives and shallots, and stir to combine; refrigerate Place the flank steak in a gallon-sized zipperlock freezer bag, add the remaining marinade, press out the air, and seal the bag Allow the meat to marinate in the refrigerator, turning occasionally, for at least hour, and up to 12 hours Remove the steak from the marinade and pat dry with paper towels Ignite a large chimneyful of coals and wait until they’re covered in gray ash, then spread evenly over one half of the grill Put the cooking grate in place, cover, and allow the grill to preheat for 5 minutes Or, if using a gas grill, heat one set of burners to high and leave the rest off Scrape the cooking grate clean Place the flank steak on the hot side of the grill and cook until well charred on the first side, about 3 minutes Flip and continue to cook until the second side is well charred, about 3 minutes longer Transfer the steak to the cooler side of the grill, cover, and cook until the center registers 125°F for medium-rare, or 135°F for medium, on an instant-read thermometer Transfer to a cutting board and allow to rest for at least 5 minutes, then carve the steak and serve, passing the reserved marinade at the table ... Transfer to a cutting board and allow to rest for at least 5 minutes, then carve the steak and serve, passing the reserved marinade at the table ...cooler side of the grill, cover, and cook until the center registers 125°F for medium-rare, or 135°F for medium, on an instant-read thermometer Transfer to a cutting board and allow to rest for at least 5 minutes, then carve