Step 1: Go to the store and buy it.
Have a landlady, a lemon tree, and a sense of adventure.
Oh, and a DIY fruit liquor kit also helps a great deal.
But according to a website I read, any clear alcohol will do. The author prefers grain alcohol to vodka, but accepts vodka as the easiest option.
The lemons come from our landlady's garden. I know they look a little orange today, but they were quite yellow last week. And from the aroma no washing can remove from my fingers, I can vouch they are, indeed, lemons rather than oranges.
And then we wait.
If it goes well, I can make anything into "Seasonal Fruit Liquor." Even avocado, according to the Japanese website, but I think I'll stick to lemons for now