The thick of it: What works best for sauces and gravies?

One of the most enjoyable parts of writing this column is the arrival of emails from readers. After talking about stews last week, I received a question about the best way to thicken sauces or gravies. Of course, the answer is: it depends.

When you’re simmering a pot of soup or stew, there’s nothing more disappointing than finding chunks of meat swimming in a thin, watery sauce. How do you fix this? There are several options, from thickening agents and pastes to the flavorful richness of a roux.

Let’s begin with one of the easiest: add a puree of one of the ingredients already in your dish or one that complements the flavors. For example, if you have a beef stew that’s too runny, boil a peeled potato until quite soft, mash it thoroughly and stir the puree into the sauce. You’ve added body and texture without altering the flavor (you will need to taste to see if you need more salt).

Another option is to create a slurry or paste made from mixing a starch with cold water. Flour is the most familiar of the alternatives, which also include arrowroot, cornstarch and tapioca flour. While the results are similar, there are some key differences to how each of these performs.

Cornstarch is pure starch, without the gluten found in flour and with twice the thickening power of flour. You will find cornstarch as a thickener in many Oriental dishes, adding a glossy sheen to the sauce. Although cornstarch blends easily and thickens immediately when added to a liquid, there are some drawbacks to cornstarch: it will not work with an acidic liquid, and it develops a spongy consistency when frozen.

Arrowroot works in a similar fashion to cornstarch, with a slightly greater thickening effect. The high gloss it creates makes it a good candidate for thickening the juices in fruit pies. Also a good choice for thickening an acidic liquid or for a dish that will be frozen, arrowroot becomes slimy when used in a dairy-based sauce.

Tapioca starch may be less familiar in this country, although it has been a staple food source in tropical climates for centuries. Derived from the cassava root, it must be ground to a pulp then drained to remove the poisonous cyanide-laced liquid (no need to worry about what’s commercially available here). Once treated, the starch can be formed into heat-soluble powder or meal, precooked flakes, or the spherical pearls used in tapioca pudding and bubble teas.

Tapioca is best for delicate foods and desserts, especially those that will be served cold or frozen. Avoid overcooking liquids that have been thickened with tapioca, or they’ll become stringy. You may find it surprising to learn that tapioca is also found in toothpaste and in biodegradable polymer packaging.

Our most familiar thickener is flour, which has some quirks we need to consider. The most obvious one is that flour imparts a floury taste unless it’s cooked. When making gravy, you can brown the flour in a dry skillet before dissolving it in water or broth and stirring it into the pan drippings. Or, you can add more depth to the flavor of your dish by stirring flour into melted butter, creating the grainy paste known as a roux.

I’ve included a recipe for a simple berry tart that calls for cornstarch (it would work equally well with arrowroot) and a basic tapioca pudding, which is far more delicious than any toothpaste you can find.

Strawberry Pie

1 9-inch pastry crust
6 C strawberries, divided
1 C sugar
1/4 C cornstarch
pinch salt
1/4 C orange juice
2 T lemon juice
2 T butter

Line the pie pan with the pastry crust, cook at 350 for about 15 minutes, just until lightly browned; set aside. Rinse, hull and halve the berries. Set aside 4 C of berries. Place remaining 2 C berries in a mixing bowl and crush with a potato masher (or puree in a blender); set aside. Combine remaining ingredients in a medium saucepan and stir to combine. Add crushed berries and simmer over medium until heated through, about 2 minutes.
Spread 2 C reserved berries in prepared pie pan. Ladle on heated berry puree. Add remaining fresh berries and shake the pan to evenly distribute the sauce. Refrigerate until set, about 4 hours.

Tapioca Pudding

2 C milk
1/4 C quick-cooking tapioca pearls
1 egg, separated
5 T sugar, separated
1/2 t vanilla

Combine milk, tapioca, egg yolk and 3 T sugar in a saucepan. Allow to sit without heat for 10 minutes. Meanwhile, whip the egg white with remaining 2 T sugar until soft peaks form; set aside. Place saucepan over medium heat and cook, stirring often, until almost boiling. Remove from heat; add vanilla and whisk in beaten egg white. Chill for 15 minutes before serving.