Baking soda roasted potatoes get their crisp edges from a simple change: slightly alkaline boiling water softens the potato surface, creating a starchy coating that browns and crisps during roasting.
Essential Concepts
Use little baking soda; drain well; avoid crowding.
Related posts: https://www.seriouseats.com/the-best-roast-potatoes-ever-recipe and https://www.bbcgoodfood.com/recipes/ultimate-roast-potatoes