Prepare a starter with the ale yeast 1–3 days in advance. For the water profile, go soft—aim for calcium 43 ppm, chloride 77 ppm, sulfate 1 ppm. Dough in with 3.5 gallons (13.2 liters) for the multistep mash: start at 122°F (50°C), rest 5 minutes; raise to 140°F (60°C), rest 10 minutes; raise to 151°F (66°C), rest 50 minutes; raise to 171°F (77°C), rest five minutes; and mash out. (If you’re unable to perform a step mash, mash at 149°F/65°C for 60 minutes.) Vorlauf until the runnings are clear, then run off into the kettle. Sparge and top up as necessary to get about 6 gallons (23 liters) of wort—or more, depending on your evaporation rate. Using lactic acid, acidify the wort to a pH of 4.8–4.9.

Boil the wort for 5 minutes, then allow it to cool to about 95°F (35°C)—or your Lacto strain’s preferred temperature, if different. If possible, purge the kettle’s headspace with CO2, then pitch the Lacto and cover tightly, sealing with plastic wrap. If possible, connect CO2 to the kettle and slowly trickle gas over the wort. Check pH hourly, starting at 8–10 hours after the Lacto pitch. Once 3.35 pH is reached, bring the wort to boil.

Boil 90 minutes, adding hops and additions according to the schedule. After the boil, whirlpool 5 minutes, add whirlpool hops, and whirlpool for another 5 minutes. Chill to about 62°F (17°C), aerate well—ideally with 10–12 mg/liter of pure oxygen—and pitch the ale yeast starter. Ferment at about 65°F (18°C) until gravity has dropped by about half, then allow the temperature to rise to about 68°F (20°C). When the final gravity has been stable for at least 2 days, drop by 9°F (5°C) per day until it reaches 30°F (-1°C), and lager there for about 10 days. Package and carbonate to 3 volumes.