Steak Sandwiches with Horseradish Mustard Butter and Watercress

• 3/4 stick (6 tablespoons) unsalted butter, softened
• 3 tablespoons drained bottled horseradish
• 3 tablespoons Dijon mustard
• 1 1/2 tablespoons minced shallot
• 1 (1-pound) piece flank steak (3/4 to 1 inch thick)
• 1 (20- to 22-inch) baguette
• 1 large bunch watercress, tough stems discarded

1. Preheat broiler.
2. Blend together butter, horseradish, mustard, shallot, and salt and pepper to taste in a bowl with a fork until combined well.
3. Pat steak dry, season both sides well with salt and pepper, and put on rack of a broiler pan.
4. Spread top of steak with 1 tablespoon mustard butter, then broil 2 to 3 inches from heat 5 minutes.
5. Turn over and spread other side with 1 tablespoon mustard butter, then broil 4 to 5 minutes more for medium-rare.
6. Transfer meat to a cutting board and let stand 5 minutes.
7. (Leave broiler on.)
8. Cut baguette crosswise into 4 equal sections, then halve sections horizontally.
9. Broil bread, cut sides up, about 3 inches from heat, rotating pan once, until golden, 30 seconds to 1 minute.
10. Holding knife at a 45-degree angle, very thinly slice steak across the grain.
11. Spread cut sides of bread with mustard butter and mound steak on half of bread.
12. Top with watercress and remaining bread.

unsalted butter, horseradish, mustard, shallot, flank steak, baguette

Taken from www.epicurious.com/recipes/food/views/steak-sandwiches-with-horseradish-mustard-butter-and-watercress-106528 (may not work)