Grilled Steak Sandwiches With Marinated Watercress, Onion, And Tomato Salad

• 1/2 cup olive oil
• 6 tablespoons white balsamic vinegar
• 1 3/4 teaspoons dry mustard, divided
• 1 tablespoon dark brown sugar
• 1 2-pound well-trimmed tri-tip beef roast
• 4 large plum tomatoes, very thinly sliced
• 1 bunch watercress, stems trimmed
• 1/2 white onion, very thinly sliced
• 6 5-inch pieces French baguette, cut horizontally almost in half, opened flat

1. Prepare barbecue (medium-high heat). Whisk oil, vinegar, and 3/4 teaspoon mustard in large bowl. Season dressing with salt and pepper. Transfer 2 tablespoons dressing to small bowl; whisk in sugar and 1 teaspoon mustard. Sprinkle beef all over with salt and pepper, then top with mixture from small bowl.
2. Grill beef until thermometer inserted into thickest part registers 120u0b0F to 125u0b0F for rare, turning occasionally, about 30 minutes. Place on cutting board; let rest 10 minutes. Cut very thinly across grain.
3. Meanwhile, add tomatoes, watercress, and onion to dressing in large bowl. Marinate while beef grills, tossing occasionally. Grill bread, cut side down, until just crusty, about 3 minutes; place on plates, grilled side up.
4. Arrange beef slices over bread. Using tongs and draining slightly, top with salad.

olive oil, white balsamic vinegar, dry mustard, brown sugar, beef, tomatoes, white onion, baguette

Taken from www.epicurious.com/recipes/food/views/grilled-steak-sandwiches-with-marinated-watercress-onion-and-tomato-salad-242965 (may not work)