Season the beef with kosher salt, then heat the vegetable oil in a large heavy pot over medium-high heat and brown the beef in batches for 8 to 10 minutes. Leave space between the pieces so you hear a steady sizzle and develop deep brown color instead of gray, wet-looking meat.

Move the browned beef to a plate and carefully remove all but 1 tbsp of fat from the pot, then lower the heat to medium and add the butter, onion, garlic, and ginger. Stir often for about 5 minutes, scraping the browned bits from the pot, until the onion looks translucent and smells sweet.

Stir in the curry powder and cook it in the aromatic butter mixture for about 3 minutes before adding the bay leaves, coconut milk, and 1 cup water. The spices should smell warm and toasty, with no harsh raw-powder aroma.

Return the beef and any collected juices to the pot, season with salt, and bring the curry to a gentle simmer before partially covering it for 30 to 35 minutes. The beef should be starting to yield when pressed with a fork, but it does not need to be fully tender yet.

Add the potatoes, return the curry to a simmer, and cook uncovered for 25 to 35 minutes, stirring occasionally and adding water if the gravy becomes thicker than you like. The curry is ready when the potatoes are tender and two forks pull the beef apart without resistance; finish with salt and serve with cilantro, sliced chile, and lime wedges.