You'll need:
4 sage leaves (from the back porch!)
6 blackberries (I bought mine at the grocery store (they're from Mexico...that's sort of local, right?), but I discovered this weekend that you can also get blackberries at the farmers' market right now.)
.5 oz simple syrup
.5 oz lemon juice (fresh squezed is best (plus squeezing lemons will make your kitchen smell awesome))
1.5 oz gin
crushed ice
club soda
Muddle the sage leaves and simple syrup together in the bottom of a mixing glass. (Muddling releases the essense of the herb into the drink. In a pinch mashing the leaves with the back of a spoon will do, but I like to use a muddler, which looks like a little bitty meat tenderizer.)
Add the blackberries and muddle some more, until the berries are mostly liquid. Add 4-5 ice cubes. Add the lemon juice and gin over the ice and stir. Strain into a collins glass. Fill the glass about halfway with crushed ice and top with a bit of club soda. (More for a smoother (more dilute) drink, less if you like booze a lot.)
Pop in a straw. And enjoy.