To make the beef rolls:
Lay a small carrot piece or half a large carrot cut lengthwise across the flat pieces of beef at the edge of the wide side closest to you so they reach edge to edge, roll up tightly and secure with wooden toothpicks.
Heat the sunflower oil in a wide nonstick skillet over medium heat. Once the oil shimmers, add the beef rolls. Sear for 3 minutes on each side until nicely browned all around, turning them as needed; they will not be cooked through; keep them moving so they don't burn, move the beef rolls to another plate.
To the same skillet add the butter and melt over medium heat. Add the flour and using a whisk stir constantly until is it lightly browned; add the water and whisk the roux. Once it starts boiling, return back the beef rolls, add the cardamom pods, salt, crushed black peppercorns and mushrooms.
Reduce the heat to low, cover up and simmer for 1 hour, you can add a drizzle of soy sauce or Worcestershire sauce for a more umami flavor.
Meanwhile, let's make the Michelin Star Mashed Potatoes:
Peel and cut the potatoes into medium sized cubes. Place in a large pot, cover with water, and cook over high heat, reduce heat to low cover up and cook for 30 minutes until tender. Drain and using a handmill or a potato ricer process the peeled potatoes until smooth and free of solid clumps. This step is essential for achieving the desired silky texture of the mashed potatoes. Add the butter, while the potatoes are still warm, folding it in gently until fully combined. Gradually, stir in the hot milk, and mix well.
Taste the mashed potatoes and adjust salt to your taste preference, ensuring it's perfectly seasoned.
Indulge in the heavenly creaminess of this Michelin Star mashed potatoes and the delectable beef rolls, happy eating.