• Harvest your green walnuts when the shells are thin and can be easily sliced with a regular kitchen knife. Use a sharp knife and be careful!
• The nuts will stain any porous surface they touch with a brownish black dye. Wear nitrile gloves if you don't want brown stained hands, and an old cutting board or a wooden one you don't mind staining.
• Slice the nuts in half or quarters, and discard any that have rot or bugs.
• As you slice the nuts, pack them into clean half gallon or quart mason jars (or other glass jars with tightly sealing lids).
  
• Once you have filled the jars, add any spices that you like (I used a few coffee beans and two or three cloves in one jar, and a cardamom pod in another). Be sparing here, you can always blend in more infused spice liqueur later if you want to change the flavor, but you can't take them out.
• Top the jars up with liqueur to cover, label the jars, and place in a cool dark cupboard or other place. Occasionally gently shake or invert the jars (more often at first to make sure everything is mixed and all the nuts are under the alcohol- top up if needed).
• Age the infusion at least six months before straining. It may taste harsh, but that will mellow with the addition of simple syrup and further aging.
• Strain the liqueur through a fine mesh strainer or chinoise, and additionally through cheesecloth, coffee filter, or filter paper if you want a very sparkling liqueur without any sediment (this may remove some color and takes a lot of patience).
• Sweeten the liqueur to taste with simple syrup (instructions below)... about one cup of simple syrup per three cups of strained infusion to make a quart.
• Bottle in an attractive bottle, and enjoy in cocktails, over ice cream, or sipped neat or over ice. Makes a nice tall drink with soda water on ice as well. The tannins will continue to soften as the liqueur ages, so if it is initially harsh, give it time and sample it again, or add more simple syrup.

Simple Syrup

• Make a strong simple syrup (2:1 ratio sugar to water) with either granulated white sugar or demerara sugar (raw sugar).
• Add a cup of water to two cups of sugar in a small saucepan, and bring the syrup just up to a boil for a few minutes to dissolve the sugar. Don't boil it longer than needed to dissolve the sugar or you risk making soft or hard caramel. Stir carefully until the sugar is dissolved- five minutes should be plenty of time.
• Let the syrup cool to lukewarm before adding it to the strained liqueur (one half cup at a time, to taste). Don't add hot syrup to your liqueur or you may evaporate off some of the alcohol.
• Store any leftover simple syrup in a boiled glass jar or sanitized container in the fridge to use in cocktails, beverages, or pastry. Discard if it becomes cloudy.