Bring a small saucepan of water to a boil. Add the diced potato and boil for 3 minutes, just until slightly softened, then drain well.
Melt the butter in a 10-inch skillet over medium heat. When it sizzles, add the potato to one side of the pan and the onion, bell peppers, and garlic to the other.
Sprinkle everything with Creole seasoning. Cook for 3 to 4 minutes, stirring the vegetables occasionally but leaving the potato undisturbed, until the potato is golden on the bottom.
Stir everything together and cook 2 to 3 minutes more, until the potato is browned all over. Taste and add salt if needed.
Notes
Use a 10-inch skillet and keep the potato in a single layer. A wider pan gives each piece room to touch the hot surface and brown. Crowd them and they steam instead, coming out soft. Cast iron holds heat well and gives the best color.Cut the potato into even ½-inch pieces. When the pieces match in size, they finish cooking together, so you avoid a mix of soft and still-firm bites.Get the butter hot before the potato goes in. It should be melted and sizzling. A hot pan sears the surface on contact, so the potato crisps instead of soaking up fat.Don't move the potato too soon. Let it cook undisturbed for 3 to 4 minutes, until a golden crust forms on the bottom, then stir. Turning it early keeps that crust from setting.