Batch size: 5 gallons (19 liters)
Brewhouse efficiency: 65%
7.5 lb (3.4 kg) pilsner
7.5 lb (3.4 kg) Vienna
4.1 lb (1.9 kg) Munich
1.2 lb (544 g) Tuoppi Kaljamallas, home-toasted dark rye malt, or caramel rye malt
1–2 quarts/liters of juniper branches in the mash
Your favorite Norwegian kveik, Lithuanian farmhouse yeast, or baker’s yeast
Mill the grains, mix in the juniper branches, and mash at 140°F (60°C) for 45 minutes. Raise the mash to 158°F (70°C) for 45 minutes, then to 176°F (80°C) for 15 minutes. Recirculate until the wort runs clear, then run off into the kettle. Sparge and top up as necessary to get about 5–5.5 gallons (19–21 liters) of wort. Do not boil; instead, cool to fermentation temperature. For kveik and Lithuanian yeast, that would be 86–104°F (30–40°C); for baker’s yeast, about 64–77°F (18–25°C). Ferment until it begins to calm down—this can take 1–3 days. When the gravity has dropped to around 1.034–1.036—or when the sahti still tastes sweetish but not cloying—crash and cold-condition for 7–10 days. Rack to kegs or serving containers, and release the pressure occasionally, if necessary. The sahti is ready to drink 10–14 days after brewing, as soon as most of the yeast have settled. It is best enjoyed fresh and still, or very lightly carbonated.
Dark rye: Tuoppi Kaljamallas is a Finnish brand of crushed dark malt (about 68°L) typically used for sahti and for kalja, a kvass-like drink, as well as for baking. It’s sometimes available in other countries via mail order. However, a good, flavorful alternative—not only for sahti, but also for other beers—is to get some rye malt and toast it yourself. At home, preheat your oven to 350°F (177°C), spread out the rye malt on a baking sheet covered in aluminum foil, and bake it for 30–45 minutes. Taste the malt after cooling, adjusting the cooking time if necessary. The goal is nutty, bready, raisin-like flavors, not coffee or chocolate. Local craft maltsters may also offer some interesting options. Caramel rye malt can also work and is widely available, though it lacks the same typical character.
Hops: Add a small amount, if you wish, but longtime sahti drinkers tend to prefer it without any hops.
Juniper: Good sahti has a light, delicate juniper flavor at most—and no juniper is better than too much. (Sahtis brewed without juniper have been known to win Finland’s National Sahti Competition.) Use the thin branch tips, which yield fewer tannins. In place of juniper, Eastern red cedar (Juniperus virginiana) is a good choice and more commonly available in much of North America. Watch out for the savin juniper (Juniperus sabina), which is toxic. Juniper berries taste different from branches, but they also work and are widely available; about 0.5–0.7 oz (15–20 g) in the mash for a 5-gallon/19-liter batch is a good starting point.