How to Make It
Heat a large cast-iron skillet over medium-high. Stir together coffee, 5/8 teaspoon salt, and 1/2 teaspoon pepper in a small bowl. Sprinkle mixture evenly over steak, pressing gently to adhere. Add 1 tablespoon oil to skillet. Add steak; cook, without moving, until bottom forms a crust, about 3 minutes. Turn steak over; cook until a thermometer inserted in thickest portion registers 120°F, 6 to 7 minutes. Remove from skillet; set aside.
Whisk together vinegar, mustard, honey, remaining 3 tablespoons olive oil, remaining 1/4 teaspoon pepper, and remaining 1/8 teaspoon salt in a large bowl. Add Brussels sprouts, pecans, and blue cheese; toss to coat.
Slice steak against the grain. Serve with Brussels sprouts salad.