Melt 3 tablespoons of butter in a cast-iron skillet over medium heat. When melted, add the chopped hot dogs and red onions and cook until onions are soft and hot dogs begin to brown, about 5 minutes. Add the chopped potato and cook until the potato begins to brown in spots, about 5 minutes. Remove from heat, season to taste with salt and pepper and keep warm.

Add remaining butter into a nonstick skillet over medium-high heat. When melted, break the eggs into the pan and cook until whites are set and yolks are runny. Divide hash between two plates, top each one with an egg and sprinkle with sliced green onions and a dollop of hot sauce.