Copying a restaurant dish from a photo alone

More than people assume. When there is a label you read it and the arithmetic does most of the work — that is the standard method. Without one you are reading the photograph instead, so look at it properly before you cook anything.

Gloss tells you about fat and emulsion. A sauce that shines has fat suspended in it; a matte sauce is thickened with starch or is a purée. Pooling at the edge of the plate means thin; a sauce that holds a ridge where the spoon dragged is thick.

Colour tells you about technique and about acid. Deep brown means browning happened. A bright, almost fluorescent red-orange in a tomato sauce usually means paprika or a chilli oil rather than tomato alone. Green vegetables that are still vividly green were cooked briefly, and probably not in the acidic sauce they are sitting in.

Char and edges tell you the heat. Blistering, leopard-spotting and dark edges do not happen in a simmer.

Cut size and shape are direct instructions. Someone chose 2 cm dice, or fine julienne, or torn rather than sliced, and that choice changes the dish.

The plate is your ruler. A standard dinner plate is 26–28 cm; a side plate is about 20. From that you can estimate the portion within about 20%, which is plenty.

Almost every cooking tradition has a standard opening move, and knowing it gets you most of the way to a plausible base.

• Italian: soffritto — onion, carrot, celery in olive oil or butter.
• French: mirepoix, often with butter; wine and stock to follow.
• Spanish: sofrito — onion, garlic, tomato, olive oil, sometimes pepper.
• Cajun and Creole: the “holy trinity” — onion, celery, green pepper.
• Much of India: onion, ginger and garlic, with whole spices bloomed in fat first and ground spices added later.
• Much of China: ginger, garlic and spring onion into hot oil, briefly.
• Thai: a pounded paste, fried in coconut cream or oil until it separates.
• Mexican: dried chillies toasted and rehydrated, blended, then fried in fat.

Identify the tradition from the plate, start with its base, and you will be closer than any amount of ingredient-guessing gets you.

Most restaurant dishes are a protein or a vegetable plus a sauce that took someone three days to build. The sauce is where the copying difficulty lives.

Ask three questions of the photograph. Is it emulsified? — glossy, opaque, clinging evenly: butter or oil beaten into liquid, kept below a simmer. Is it reduced? — dark, syrupy, coating the back of a spoon: stock or wine simmered down for a long time, and there is no shortcut worth taking. Is it a purée? — uniformly matte and thick right to the edge: blended vegetables, and you can match it in twenty minutes.

Then taste your memory: sharp, sweet, bitter, deeply savoury? That tells you what went into it after the base — vinegar, wine, citrus, honey, roasted bones, soy, fermented anything.

This is the most underused technique in the entire business. Ask the waiter what is in it. Many kitchens are proud of a dish and perfectly happy to tell you it has miso in the butter, or that the crunch is fried buckwheat.

You will not get the full recipe and you do not need it — you need the two ingredients you would never have guessed. Those are exactly the ones that make your version taste “nearly right” instead of right.

If asking is not an option, the menu description is a partial ingredient list written by the chef. Read it as one.

There will be things you cannot know. How much salt. Whether the stock was chicken or veal. Whether the sweetness is honey or reduced onion.

Guess, cook it, and write down what you guessed. A recipe with three lines marked “assumed — check next time” is a working document; the same recipe with those three lines presented as fact is a trap you set for your future self.

This is also how the app handles it. Copying from a photo of a plate rather than a label means there is no ingredient list to lean on, so DishCopy marks clearly which parts were filled in on the basis of how such a dish is normally made, and it asks you about the choices — heat, richness, servings — instead of silently deciding.

Takeaway and delivery food sits between the two extremes. There is usually no ingredient list, but there is something better: a large volume of a sauce you can examine, taste cold, and even separate.

Let some of it settle in a clear glass. You will see how much fat rises, whether there is starch settling out, whether there are whole spices at the bottom. Taste it cold, when the aromatics are quiet and the salt and acid are obvious. It is not elegant, and it works.

Once you have something cookable, stop copying and start deciding — the changing-it-on-purpose guide is the point of all this.