the goods:
1/2 cup Dijon mustard
3 tablespoons fresh lemon juice
1 garlic clove, crushed through a press
1 large sirloin steak, trimmed and cut into 4 equal portions
1 pound red new potatoes, halved (quartered if large)
3 tablespoons olive oil
1 bunch asparagus, trimmed of woody ends
Preheat oven to 450 degrees. In a small bowl, stir together mustard, lemon juice, and garlic; season with salt and pepper. Place marinade in a resealable plastic bag. Add steaks, and rub to coat. Let steaks marinate at room temperature 10 minutes, or refrigerate up to 1 day.
On a large, rimmed baking sheet, toss potatoes with 1 tablespoon oil; season with salt and pepper. Roast 15 minutes, then add asparagus to sheet, and toss with another tablespoon oil; season with salt and pepper. Roast until potatoes and asparagus are tender, 10 minutes more.
While vegetables are roasting, heat remaining tablespoon oil in a cast-iron skillet over medium-high. Remove steaks from marinade, allowing excess to drip off; cook until you've reached your desired doneness. Let steaks rest 5 minutes before slicing.
