11. Form ground chuck into four thin rectangular patties, making them slightly larger than bread slices. Season aggressively with kosher salt and cracked black pepper.
22. Heat cast-iron skillet over high heat. Add bacon grease and sear patties until deeply caramelized, about 3-4 minutes per side. Achieve medium-rare doneness with crispy exterior.
33. Meanwhile, butter sourdough bread generously on exterior sides. Toast in separate skillet until golden brown and crispy, about 2-3 minutes per side.
44. Layer patties with American and Swiss cheese, allowing cheese to melt slightly from meat's residual heat.
55. Spread Thousand Island dressing generously on inner bread surfaces.
66. Assemble sandwich by placing cheesy patty between toasted sourdough, pressing gently to integrate flavors.