Preheat your oven to 400F/200 C and line a baking sheet with parchment paper. Peel the turnips and cut them into strips. Transfer to the baking sheet.
Drizzle 1 tbsp of olive oil and add the garlic powder, onion powder, ½ tsp salt, and ¼ tsp black pepper. Toss to coat evenly. Transfer the baking sheet to the oven.
Bake for 15 minutes, then flip the fries and bake for another 10-15 minutes. They should be done when golden and crispy on the outside and soft in the middle. Take out of the oven and let cool slightly.
To a small bowl, add the butter, lemon juice, mustard, and Worcestershire sauce. Finely chop the chives, mince the garlic, and add them to the bowl. Stir to combine thoroughly.
While the fries are baking, prepare the steak. Season the steak generously with salt and pepper. Place a cast-iron skillet over high heat and add 1 tbsp olive oil.
Cook the steaks for about 5-8 minutes in total depending on the thickness, turning frequently. It is done when it is browned on both sides and firm but still easily yielding to the touch. Rest for 10 minutes.
To serve, add a steak to each plate and top with half the butter. Divide the fries into 2 and place them next to the beef. Serve immediately.