Say, for instance, that a recipe calls for the use of chicken or beef stock, and you don’t have any—what do you do? Quit, obviously. You are swine and do not belong in a kitchen, you worthless pile of elephant dung. In most cases, you may simply use water and compensate by being a little heavier-handed with the spices. For something such as a soup, this is perfectly acceptable, and no one will know the difference. Where this becomes a problem is when you need to reduce the stock, like when making a sauce. So, what then, is the function of stock? This is the type of question that you should be asking yourself whenever faced with a substitution.
Stock is slightly more viscous that plain water. For a soup, this means that each spoonful will linger on the tongue a hair longer (think chicken noodle). When hot, though, meat stocks and water are of more-or-less the same viscosity, and most diners would not notice a difference. When chilled, however, the difference is very clear. A well-made stock will set like Jello at refrigerator temperatures because of its gelatin content. Not many foods are eaten chilled, so viscosity is rarely a factor (the difference will not be discernible in anything thicker than a watery soup like French onion, or chicken-noodle). In something like creamy tomato soup, the cream and puréed tomatoes will thicken the soup far more than the stock ever would. In a case like this, the stock is used as a way of adding some complexity of flavor to the dish. Still, this addition of flavor is relatively slight if the stock is used in its unreduced form. Thus, if your recipe calls for stock that does not need to be reduced, simply use water and beef-up the spices/seasonings.
In sauces, a stock is often reduced to the point where it thickens and the flavor is greatly concentrated. Unfortunately, if you do not have stock, you will not be able to make that particular sauce. That said, there are many, many sauces out there, and there is a good chance that the one you choose to use will be better than the original. One option is to make a roux-based sauce. This is nothing more than cooked butter and flour. Take equal parts butter and flour (in tablespoons) and heat in a pan on medium heat for a minute or two, making sure the flour absorbs all the butter and that there is no dry flour left (and don’t let it burn—though it’s ok if just starts to brown (don’t tell the French we said that!). After a minute or so, add some kind of liquid (water, milk, wine, beer—we don’t care, it’s all good!) and seasonings. Bring the contents of the pan to a boil over medium-high heat, and stir until it thickens. The thickening will be quite sudden, so don’t walk away. Starches (in this case from the flour) can absorb many times (up to 30 times, for some) its weight in water, and begins to do so around 158ºF for potato starch, 185ºF for tapioca, and 212ºF (boiling) for wheat flour and cornstarch. Use any of these starches, including the blended or finely-crumbed baked/cooked versions of these (breads, crackers, tortillas) whatever floats your boat!
Substitutions are often viewed as inferior, but that way of thinking inhibits creativity. It’s far better to think of them as ‘modifications’ to the recipe–much more chefy! New and better dishes are created because the “right” ingredients weren’t around all the time, so think of your shopping blunder as an opportunity rather than an annoyance. Good luck!
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