Slice the steak into thin strips.
Season generously with salt and pepper.
Heat half of the ghee in a large, oven-safe casserole dish or skillet over high heat.
Working in batches, quickly fry the beef strips on both sides until well browned.
Remove the beef from the dish and set aside.
Reduce the heat to medium-high.
Add the remaining ghee and the chopped onion to the dish.
Cook for 5 to 8 minutes, until softened and lightly browned.
Stir in the garlic, crumbled bay leaves, celery, and leek, and cook for another 2 minutes until fragrant.
Add the mushrooms, broccoli, broth, sour cream, paprika, and cayenne pepper.
Stir to combine, then cover with a lid.
Reduce the heat to medium-low and let it simmer for 5 to 6 minutes, or until the broccoli is tender-crisp.
Remove the dish from the heat.
Stir the cooked steak back into the vegetable mixture.
Sprinkle the grated Swiss or Cheddar cheese evenly over the top.
Place the casserole under a preheated broiler on high. Broil for about 5 minutes, or until the cheese is completely melted, bubbling, and golden brown.
Carefully remove from the oven and let it cool for a few minutes.
Garnish with fresh herbs before serving.
Don't crowd the pan when browning the beef.
Cook it in batches to ensure each piece gets a beautiful, flavorful sear rather than just steaming.