I make dinner for an extended family group on a Friday, which can be up to 10 adults (including two healthy teenagers) and five youngsters (aged from almost 5 to 12). I like to make a nice meal, so it's only occasionally a roast with vegetables and salad, (which is nice!) but mostly comes from a recipe that I have picked up from a magazine or the newspaper or from a recipe book. Because of the numbers, I often double or treble the recipe, and what happens from time to time is that this doesn't always work, and I end up with too much of some ingredient, or some part of the meal. Is there any formula that I could apply to this doubling/trebling process, or could you suggest ways of dealing with it?Briar
How lucky are your guests that they’re being fed such lovely and well-thought out meals. I have to say I’m a real fan of serving stews and hearty soups at this time of year for large groups as those recipes are always quite forgiving. If you add another sliced carrot, diced parsnip or tablespoon of fresh herbs, no-one would ever know and the recipe won’t be affected at all. When it comes to increasing other recipes though, things can go off the rails slightly.
Some of the many things that can gowrong when doubling or trebling a recipe is the proportion of liquids, salt and spices being used. I once had it explained to me by a chef in a commercial kitchen and it boils down to this. If you were making a cake for 12, and you doubled the recipe of a cake for six, you wouldn’t double the temperature. You would make it in a bigger tin and cook it longer but it wouldn’t be cooked for twice as long. That may seem obvious, but hidden in there is the gem that simply by doubling everything in a recipe won’t always give you what you’re after.
I recall a salmon teriyaki skewer marinade recipe I put in my last cookbook Everyday; it uses (for 4 starters) 600g diced salmon to 125ml soy, along with mirin, chopped ginger and sesame oil. This amount of soy is just right for this amount of salmon. But if you were to make enough skewers for 40 (i.e. 10 times the recipe), and use 6kg diced salmon, you'd only need around 650ml soy (around 5 times the recipe). The reason is that any more soy and your fish would drown in it and it would begin to overpower the fish. This has more of a physics reasoning to it — all to do with the surface area of the salmon in relation to the volume of liquid — but at this point it might all seem a little too far away from cooking. If you follow a recipe for mayonnaise or hollandaise, a recipe might say "serves 4-6". The reality is that it might actually serve enough for 8, but it's very hard to make an emulsified sauce with, say, 1½ egg yolks, so a recipe might be stepped up to use 2 eggs. Multiply that by 4 and you've suddenly got a sauce for 32, not 16. The leftovers on a single recipe will be insignificant, but on a scaled-up recipe will just seem like a lot of waste.
As to a formula that will always work — I’m afraid to say that it just doesn’t exist. A good cook, and I imagine you are one, will soon realise that there is always a good amount of tweaking a recipe for a lot of to get it just right.
What I would say though is that you do need to follow the following points when scaling up recipes.
Seasoning — add 30 per cent less than the recipe states at the beginning, and then when the dish has almost finished cooking, taste and adjust it.
Ovens— a single roast chicken, for example, will cook quite differently than 10 cooked in the same oven as there will be less hot air flowing around the birds. More birds in the oven will produce more moisture which means slower cooking, but more succulent cooking. Simply turning the oven up won't help. So be prepared to cook for longer times.
Liquids — add only 90 per cent of liquids to a recipe when scaling up by more than three times. You can always add more liquid to something, but it's impossible to remove the excess. This applies especially to something like a beer batter which you want to be "just right" in thickness, or a pickle recipe where in many ways the amount of liquid might be determined by the size of jar you use.
I realise this hasn’t exactly answered your question, but then cooking is a combination of following a recipe, science and common sense and sometimes the latter is far more important than the former.
In our Ask Peter series, executive chef Peter Gordon answers your curly culinary questions. If you’re stumped over something food-related, send your question to askpeter@bite.co.nz and keep checking in for answers. You can read more on Peter on his website, have a read of his Ask Peter articles or check out his recipes on our site.