You can double this recipe for 8 servings, but you'll need a really large, deep skillet. I find it much easier to cook 4 servings in a regular 10" skillet.
Scrub the potatoes clean and dry well, then transfer to a baking sheet. Bake for 45-60 minutes or the potatoes are tender when poked with a fork or knife.
About 10 minutes before the potatoes are done, start cooking the vegetables. Add the oil to a large skill and heat over medium-high heat.
Stir in the onion and peppers and cook 5-7 minutes or until just starting to soften. Remove to a plate or bowl.
Remove the potatoes from the oven and let cool until you can handle them. Cut into 1" cubes. Note: I do not peel my potatoes, but you can if you wish.
Add butter to the skillet over medium-high heat and melt. Add the potatoes and spread out evenly. Sprinkle liberally with salt and pepper.
Cook for 5-7 minutes, without stirring, or until the bottoms of the potatoes just start to get crispy. Flip gently, season again, and continue cooking, without stirring, another 5-7 minutes or until the bottoms just start to get crispy. If the potatoes get too dry add more butter and stir gently.
Add the vegetables back in. Stir the mixture and heat thoroughly for 5 minutes.