Wash and dry all produce. Adjust rack to middle position and preheat oven to 425 degrees. Take out 1 TBSP butter and let sit at room temperature. Peel potatoes, then cut into 1/2-inch cubes. Thinly slice garlic. Finely chop parsley. Pat steak dry with a paper towel.

Toss potatoes on a baking sheet with a drizzle of oil and a pinch of salt and pepper. Roast in oven until browned and tender, 20-25 minutes total (we’ll add more to the sheet before the potatoes are done).

Heat a drizzle of oil in a large pan over medium-high heat. Season steak with salt and pepper. Add to pan and cook until browned, 2-3 minutes per side. Remove baking sheet from oven and give potatoes a toss. Add steak to sheet, return to oven, and roast to desired doneness, 5-7 minutes. Remove steak from sheet and let rest 5 minutes.

Meanwhile, heat a drizzle of oil in pan used for steak over medium heat. Add green beans and cook, tossing, until tender but still a little crisp, 4-5 minutes. Add garlic and cook until fragrant, about 30 seconds. Season with salt and pepper.

Mix butter, 1 tsp mustard (we sent more), and a pinch of parsley in a small bowl. Season with salt and pepper.

Slice steak against the grain and divide between plates. Top with herb butter. Serve with green beans and potatoes on the side. Garnish with any remaining parsley.