Heat a large cast-iron skillet over medium for 3 minutes. Add oil and swirl to coat; add potatoes and arrange in an even layer. Sprinkle evenly with salt. Cook, undisturbed, until lightly browned on the bottom, about 3 to 4 minutes. Stir potatoes and continue to cook, stirring occasionally, until mostly tender, about 4 to 5 minutes. Transfer with a slotted spoon to a plate.
Without wiping skillet clean, add onion and bell pepper; cook, stirring occasionally, until starting to soften, about 3 minutes.
Add beef and cook, stirring often to crumble, until browned, about 5 minutes. Drain, if necessary. Return beef to skillet.
Stir in potatoes, garlic, ranch seasoning, and smoked paprika into same skillet; cook, over medium, stirring constantly, until fragrant, about 1 minute.
Stir in chicken broth, sour cream, and Worcestershire; cook, stirring constantly, until starting to thicken, about 2 minutes. Continue cooking, stirring occasionally, until potatoes are tender, about 2 more minutes.
Remove from heat and top evenly with cheese; let stand until cheese melts, about 3 minutes. Serve with hot sauce and sprinkle with scallions.
