From Kenji
The Crispiest Roast Potatoes
Kenji's method, built on one Heston Blumenthal figured out first: boil the chunks with a little baking soda, rough them up into a shaggy slurry, then roast in garlic-rosemary oil until they shatter. A side dish, technically, but a plate of these plus fried eggs or a steak is dinner with applause.
75 minutes · serves 4
Ingredients
Equipment
big pot · sheet pan · colander · small saucepan (for the oil) · large mixing bowl · spatula
The steps
- 1
- 2
- 3
- 4
- 5
- 6
Cook Mode walks these one at a time, with timers and a way out when things go sideways.
The idea
Rough surfaces crisp; smooth surfaces don't. Crunch isn't luck, it's manufactured: break the surface down, then give it fat and uninterrupted heat.
Why it works · Kenji
- Baking soda makes the boiling water alkaline, which dissolves the pectin glue in the potato's surface — the outside breaks down while the inside stays intact.
- Rough tossing rubs that loosened starch into a shaggy slurry coating: enormously more surface area, and surface area is where crisp happens.
- Infusing the oil separately gets garlic and rosemary flavor into the fat without incinerating the solids at 450°F.
- Big chunks keep the crisp-to-fluffy ratio honest — all crust and no interior is a potato chip, and you can buy those.
- Deep brown, not golden: browning compounds ARE the flavor, and most home cooks pull potatoes five shades early.
Tested against plain-water parboil and no parboil at all: plain water gets you 80% there if you rough them up hard; raw-to-oven gets you a decent potato with a merely fine exterior. The baking soda batch is the one people remember.
Substitutions
- russets / Yukon Golds → red potatoes work in a pinch. They're waxier, so the slurry forms less eagerly — boil 2 minutes longer and toss harder.
- baking soda → skip it and rough them up extra hard. Genuinely 80% as good. The soda is the last 20%.
- rosemary → thyme, sage, or nothing. The technique doesn't care about the herb.
- olive oil → duck fat or beef fat if you ever have it. Best version there is. Olive oil is a very close second; any neutral oil is fine.
Tomorrow
- Breakfast potatoes — re-crisp in a hot dry skillet 5 minutes, fried eggs on top.
- Chop into a fridge frittata or fold into tomorrow's taco night.
3 days in the fridge. They will go soft; that's physics, not failure. Eight minutes in a 450°F oven brings most of the crunch back. Reheat in a hot, dry pan so the crust comes back. The microwave makes steam.
Make ahead
Parboil and rough them up to the end of the tossing step, then hold on the sheet pan in the fridge up to a day. Straight from fridge to hot oven works — add 5 minutes.