1 tablespoon whipped or regular butter, slightly softened
3 teaspoons extra-virgin olive oil, divided
1 tablespoon minced fresh chives, or shallot
1 tablespoon capers, rinsed and chopped
3 teaspoons minced fresh marjoram, or oregano, divided
1 teaspoon freshly grated lemon zest, divided
1 teaspoon lemon juice
3/4 teaspoon kosher salt, divided
1/2 teaspoon freshly ground pepper, divided
1 tablespoon minced fresh rosemary
2 cloves garlic, (1 minced, 1 peeled and halved)
1 pound filet mignon, about 1 1/2 inches thick, trimmed and cut into 4 portions
4 slices whole-grain bread
4 cups watercress, trimmed and chopped
1. Preheat grill to high.
2. Mash butter in a small bowl with the back of a spoon until soft and creamy. Stir in 2 teaspoons oil until combined. Add chives (or shallot), capers, 1 teaspoon marjoram (or oregano), 1/2 teaspoon lemon zest, lemon juice, 1/2 teaspoon salt and 1/4 teaspoon pepper. Cover and place in the freezer to chill.
3. Combine the remaining 1 teaspoon oil, 2 teaspoons marjoram (or oregano), 1/2 teaspoon lemon zest, 1/4 teaspoon salt and pepper, rosemary and minced garlic in a small bowl. Rub on both sides of steak. Rub both sides of bread with the halved garlic clove; discard the garlic.
4. Grill the steak 3 to 5 minutes per side for medium-rare. Grill the bread until toasted, 30 seconds to 1 minute per side. Divide watercress among 4 plates. Place 1 toast on each serving of watercress and top with steak. Spread the herb butter on top of the steaks and let rest for 5 minutes before serving.
1. MAKE AHEAD TIP: Prepare herb butter (Step 2), wrap in plastic wrap and freeze for up to 1 month.