What the heat is for
A stir-fry works by cooking the surface of small pieces of food faster than the interior can overcook, and by evaporating any liquid the moment it appears. Both require the pan to stay very hot even as cold food is dropped into it.
A commercial wok burner delivers enough power that the pan recovers instantly. A domestic hob does not: put a kilo of cold vegetables into a wok on a home ring and the temperature collapses, the food releases water, and you are boiling. That is why home stir-fries so often come out wet and grey, and it is not a technique failure so much as a physics one.
Everything below is about working around it.
How to compensate at home
- Cook in small batches and combine at the end. Half the quantity is more than twice as good.
- Preheat properly. Get the empty pan hot enough that it just begins to smoke before any oil goes in. This takes longer than you expect.
- Use a flat-bottomed carbon steel pan or a heavy skillet, not a round-bottomed wok balanced on a ring, which touches the flame in one small spot.
- Cut everything small and uniform, and cut across the grain for meat.
- Have absolutely everything ready — sauce mixed, aromatics chopped, plates out. Once it starts there is no pausing.
- Dry the ingredients. Wet vegetables and marinated meat straight from a bowl of liquid will not fry.
- Add ingredients in order of cooking time, hardest first, and take the meat out and return it at the end.
The sequence
- Heat the pan until it smokes faintly. Add oil and swirl it up the sides.
- Sear the protein first, in one layer, until browned. Take it out and set it aside.
- Add more oil, then the aromatics — garlic, ginger, spring onion whites — for ten to twenty seconds only. They burn fast.
- Add the hard vegetables and toss constantly for a minute or two.
- Add the softer vegetables and any greens.
- Return the protein, add the pre-mixed sauce round the edge of the pan so it sizzles, and toss to coat. Thirty seconds.
- Off the heat, finish with sesame oil, spring onion greens or a splash of vinegar. Serve immediately.
The preparation that makes it work
- Velveting
- Meat tossed with cornflour, a little egg white and soy, and left for fifteen minutes. Comes out noticeably tender, and the coating thickens the sauce.
- A pre-mixed sauce
- Soy, stock, sugar, vinegar and cornflour whisked in a small bowl beforehand. Adding these separately mid-stir-fry does not work.
- Aromatics ready in one dish
- Garlic, ginger and chilli chopped and together, because there is no time to reach for three things.
- Blanching hard vegetables
- Broccoli, carrot and green beans briefly boiled first, so they need only seconds in the pan.
- Everything within arm's reach
- The whole cook is under five minutes and most of the skill is in the ten minutes before it.
Common questions
Do I need a wok?
No. A large heavy skillet on a domestic hob often works better than a round-bottomed wok, which only touches the heat at one point. A flat-bottomed carbon steel wok is the best compromise.
What is wok hei?
The slightly smoky, seared aroma of a restaurant stir-fry, produced when oil and food vapour ignite at the pan surface. It genuinely requires more heat than a domestic hob provides.
Which oil?
Something neutral with a high smoke point — groundnut, rapeseed, sunflower. Sesame oil is a finishing flavour and burns quickly.
Why is my stir-fry watery?
Too much in the pan, wet ingredients, or not enough heat. In that order.