Cured salmon, gravlax, what have you.

From R., 18 December 2009, Curing salmon: which recipe is best?

Q: I lost my favorite recipe for cured salmon and am seeking a replacement. Got a recommendation? I’ve been looking at recipes for gravlax, and the variations are confusing me (for comparable amounts of fish, one uses less salt/sugar and cures for 3-4 days, whereas another uses four times as much but only 30 hours).

A: Thanks for your question. Harold McGee notes that salt/sugar ratios, quantities, and curing times for salmon vary widely. Out of curiosity, I poked around through a number of cookbooks and various reliable internet sources and found the same thing – sources disagree. My own cure formula is simple – equal quantities by weight of salt and sugar, three days under weights.

Let’s consider the science behind the cure, and you can decide if this works for you. Salt cures work by drawing moisture out of the meat/fish – as moisture leads to spoilage, reducing the amount of water in a food will increase its viability. To get sciencey on you, if you place a dry salt cure on a food product, the salt concentration on the inside and outsides of the food will differ greatly. To equalize the concentrations, salt will diffuse into the food, and water out through osmosis, until the salt levels are the same on both sides (this normally takes place at the cellular level). Accordingly, the higher the salt concentration, the more liquid the cell will expel, and the longer the exposure to the cure (to a point), the longer the opportunity to reach equilibrium. In food preservation, the goal is to achieve a product water activity (A(w)) level that is low enough to inhibit parasite growth. Bacteria are inhibited at a certain level, but yeast and mold may continue to survive to a lower A(w) level.

Sugar works the same way, as you may know if you make jams or other preservatives, but in the case of meat preservation, the salt is more important. Instead, in the meat preservation context, sugar generally provides flavor and counteracts the harshness of salt.

So, now that you’ve received this erudition, consider your goals. Are you looking for a firmer texture? Then you want a longer cure, so the salmon will expel more liquid. More salt, or a sweeter taste? You can vary the balance of salt and sugar to some degree. Realistically, you’re not looking to preserve salmon long-term – gravlax still requires refrigeration – so the quantity of cure isn’t super important. Are you trying to deliver other flavors to the salmon as well? If so, alcohol is useful, especially flavored alcohol like aquavit or gin, but not traditional. Although pine needles apparently were the classic gravlax flavoring (according to McGee), modern gravlax usually features fresh dill – in this case, if you use alcohol, avoid a strongly flavored alcohol, which will compete with the dill. Select vodka instead.

Basic gravlax

3 oz kosher salt
3 oz table sugar (sucrose)
2 tablespoons cracked white peppercorns
1 fresh, clean, skin-on salmon fillet, any pin bones removed, about 2 1/2 lbs
2 to 3 large bunches fresh dill, coarsely chopped, including stems OR if you have access, about 1 c fresh pine needles, washed well. Yes, pine needles are safe, and you can choose from among a number of varieties

Optional: 50 ml/2 tbsp gin or aquavit, skip the dill, and add 1 tsp cracked juniper berries to the peppercorns

Combine the salt, sugar, and peppercorns in a small bowl. Rub a handful of the mixture on both sides of the salmon, place it in a shallow pan. Cover the top (non skin side) with any remaining mixture and then place the dill or pine needles on top. If you are using alcohol, drizzle over the surface evenly. Wrap in plastic and stand in a cool (40-55F if possible) area for about 3 hours. Then place a shallow pan on top that covers the length of the salmon, weight the pan, transfer to the refrigerator, and cure for 3 days. Halfway through, drain off any liquid and turn the salmon under the weight.

When ready to serve, wipe any remaining cure from the gravlax with a paper towel (a moist towel is best). Slice thinly on the bias. Well wrapped, this salmon will last about 10 days under refrigeration; alternatively, you may divide it immediately after curing and wrap portions to freeze – they will last several months in the freezer.