Martha's recipe calls for ginger ale as the mixer (delicious!). I don't drink much soda of any sort - it's just too sweet for me, so I did a second batch with sparkling water as the mixer- great for those of you avoiding soft drinks. For some it might make sense to keep the components separate (instead of combining everything in one pitcher - making it easy to mix each drink to order. This way each person can control their own level of flavor/sweetness. Martha also includes a side bar of helpful notes related to this recipe - berries can be pulsed briefly in a food processor and strained. Be careful not to crush the seeds, as this adds a dirty taste to the blackberries. You can freeze blackberries in ice cubes for a nice accessory to the drink. The sugar syrup can be transferred to a metal mixing bowl set in a bowl of ice to cool it down quickly. For a wonderful frozen cocktail, puree ice and a jigger of gin with the blackberry-lime mixture in a blender.
4 cups fresh blackberries, or unsweetened frozen blackberries, thawed, plus extra for garnish
1 cup turbinado sugar, natural cane sugar, or grated palm sugar
1 kaffir lime leaf, crushed, or 1 tablespoon grated lime zest
1 green cardamom pod, lightly crushed
1/2 cup fresh Key lime juice (about 8 -12 limes)
Thin lime slices, for garnish
2 cups ginger ale (hs note: or sparkling water)
Lay a doubled piece of cheesecloth on a nonporous work area. (As the berries will stain a wide array of cutting surfaces and clothes, this may be best done outside or over newspaper and wearing an apron or smock.) Place the blackberries on top of the cheesecloth and gather into a bundle like a hobo sack. Hold the sack of berries over a glass, stainless steel, plastic, or ceramic bowl. Twist the top of the sack to squeeze the juice from the berries into the receptacle. (This will yield about 1 cup very strong, tart, dark juice.) Refrigerate the juice until needed; discard the purple mash.
In a small saucepan, combine the sugar, 1 cup water, the lime leaf, and the cardamom pod. bring to a boil. Simmer over low heat for 10 minutes, or until the mixture is reduced to a thin syrup. Remove the lime leaf and cardamom. Allow the sugar syrup to cool and then chill it.
In a 1-quart pitcher, combine the blackberry juice, sugar syrup, and lime juice. Stir to combine and then refrigerate until cold.
To serve, stir the ginger ale (or water) into the pitcher, fill glasses with ice, and pour in the blackberry limeade. Garnish with slices of lime.