This drink is so yummy I usually have to make a double or triple batch.
1/2 cup honey or you could use any other sweetener
1 piece unpeeled ginger, about 1 1/4 in. by 1 1/4 in., sliced into 1/8-in.-thick coins
1 sprigs rosemary (5 in. each), plus 8 sprigs (1 1/2 in. each) for garnish
1 cup fresh lemon juice (at least 5 lemons)
1 1/2 cups soda water
Make lemon concentrate: In a medium saucepan, bring honey, ginger, 5-in. rosemary sprigs, and 2 1/2 cups water to a boil. Reduce heat to a simmer and cook, stirring occasionally, about 10 minutes. Let steep at room temperature 20 minutes. Strain into a medium bowl, discarding rosemary and ginger, and stir in lemon juice.
Fill a large pitcher half-full with ice cubes. Pour in soda water and lemon concentrate and stir vigorously. Serve with a rosemary-skewered lemon quarter in each.