Ingredients

   
150g neutral oil (canola, vegetable, rice bran)
1 egg, cold from the fridge
  jasmine rice, to serve
  prik nam pla or fish sauce, to serve

Steps

  1. Wipe the skillet dry. Crack the egg into a small bowl or ramekin.

  2. Pour the oil into a 6.5–8 inch cast iron skillet — it should stand about ¼ inch deep — and heat over medium to 350°F. Use a thermometer; cast iron gives no visual warning before it overshoots.

  3. Hold the lip of the bowl against the surface of the oil and slide the egg in. Do not drop it from height. It will bubble hard and the white will puff immediately. Do not move it.

  4. Fry 30–60 seconds, spooning hot oil over the white as it sets. Hold the oil between 325°F and 350°F. Pull the egg when the edges are brown and blistered and the yolk is still liquid.

  5. Lift with a slotted spatula, tilt to drain, and rest it on a rack or paper towel. Serve on rice with prik nam pla.

Notes

  • Khai dao (ไข่ดาว). Also eaten on pad kra pao or torn into yum khai dao, the fried egg salad.
  • The crisp and the soft center are the same 30–60 seconds. The edge of the white spreads thin across 350°F oil, its water boils off, and the proteins brown before enough heat reaches the yolk to set it. Past about a minute the yolk goes. Basting is the dial: spoon oil over the white for a liquid yolk, over the yolk to film and set it. Flipping ends the question.
  • Cast iron is not the traditional pan — a wok is, and no published khai dao recipe found uses cast iron. What it buys is thermal mass: a fridge-cold egg pulls heat out of 150g of oil fast, and a thin pan drops out of the 325–350°F band, which gives a leathery edge instead of a crisp one. What it costs is correction speed, so set the temperature before the egg goes in, not after.
  • Sticking is not the problem it is with a butter-fried egg. At ¼ inch and 350°F the white sets the instant it lands and the egg rides on the oil rather than bonding to the iron.
  • Spatter is the egg’s water, not the oil. Egg white is ~88% water; hitting 350°F it flashes to steam, expanding roughly 1,600x, and the bursting bubbles throw oil. Four levers, in order of effect: a dry pan (a bead of water in ¼ inch of 350°F oil is the violent case); sliding the egg in from a ramekin held at the surface instead of dropping it; a small deep-walled skillet, which holds spray that a flared wok throws over the rim; and a mesh spatter screen — not a lid, which condenses the steam and drips water back into the oil. None of the published recipes address this at all.
  • A cold egg is deliberate: a colder yolk needs more heat to set, so the edge has longer to crisp before the center does. Not tested side by side against a room-temperature egg.
  • One egg at a time. Two in the same pool drop the oil temperature and their whites fuse into one sheet.
  • Scale the oil to the pan, not the recipe — ¼ inch is the target, so a 10 inch skillet needs about 200g.
  • Strain the oil and reuse it once or twice. It carries egg flavor, so keep it for eggs.
  • A wok works and is traditional: same oil depth, same 350°F, swirl the oil against the egg instead of spooning it. Expect more spatter outside the pan.