The biggest difference between lager beers and ales or pilsners is the temperature used to finish them. “Lagering” simply means keeping the beer cold while it ages. This is what gives lager its particular flavor and its clear amber color. The other main difference between lagers and other beers is the yeast. Lager yeast is specially formulated to produce lager’s light, delicate flavours; the cold aging simply enhances this process.
Pour about 1/4 lb. of crushed crystal malt extract (not the dry malt) into a square of cheesecloth and tie it into a bundle, or pour the same amount into a canvas drawstring bag. Immerse the wrapped malt in the water and simmer until the water turns a light golden tan. Remove the bag, squeeze it lightly and set it aside on a towel.
Fill your brew kettle or large stew pot with about 2 gallons of water. Over medium-high heat, bring it to a simmering temperature of about 160 degrees. Turn the heat down to medium to maintain temperature.
Sterilise all of your equipment by pouring, swirling and immersing it in boiling water. Do not use soap; this will change the taste, and some soaps are toxic. The heat should kill off 99 percent of germs. Clean your work area, too.
Bring the water to a boil and remove it from heat. While the water is still hot, add about 6 lbs. of crushed crystal malt. Add about 2 cups at a time, stirring constantly to dissolve it. Place the water back on the heat and bring it to a boil.
Pour about 2 oz. of hops onto a square of cheesecloth and slip it into the boiling water. Boil the hops for 45 to 60 minutes to fully extract the flavours. Nearby, fill a large sink halfway with cool water and ice.
Place the kettle in the sink, making sure the ice bath does not pour into the kettle. Check the mixture about every 10 minutes; when it cools to about 80 degrees, remove it from the bath. Remove the hops bag and set aside.
Pour the water mixture into a 5-gallon plastic bucket with a lid. Add one packet of lager yeast and 2 to 4 lbs. of corn sugar along with enough water to fill the bucket. Place the lid on the bucket securely and shake or rotate it to mix in the yeast. Lock the airlock into the bucket lid.
Place the bucket in your lager refrigerator and lower the temperature to about 55 degrees. After about two weeks, raise the temperature to between 60 and 65 degrees. Use cheesecloth to strain the beer into a fresh bucket with a lid. This helps keep the flavour fresh and light.
Put the new bucket back into the lager fridge. Each day, lower the temperature from the starting temperature of 60 to 65 degrees about 5 degrees until you reach between 35 and 40 degrees. Let the lager sit and work for six weeks to 18 months to achieve a good lager flavour. Six weeks is long enough for the lagering process to just finish; if you want a fuller lager flavour, age it a year to 18 months.