How to Make It
Place potato slabs in a medium saucepan, and add water to cover by 2 inches. Bring to a boil over medium-high. Add 2 tablespoons salt, reduce heat to medium-low, and simmer until potatoes are just tender but not falling apart, 10 to 12 minutes. Drain well, and pat dry.
Place oil and butter in a large skillet over medium-high, and cook until butter is melted. Add potato slabs, and cook until browned and crusty, about 5 minutes per side. Transfer to a platter, and season with pepper and remaining 1/2 teaspoon salt.