1¼ cups sugar
6 ounces raspberries, plus more for garnish (about ¾ cup)
1 cup water
1 cup lime juice (juice of 16-25 limes— I used bottled juice)
1½ liters seltzer water
1 lime, thinly sliced, for serving
Combine the sugar, raspberries, and water in a small saucepan. Bring the mixture to a simmer. Stir until the sugar dissolves. Press the berries with back of a wooden spoon so their juices leach into the mixture. Let sit and steep until cool. Strain, discarding the solids.
Combine the cooled raspberry syrup, lime juic and seltzer in a large pitcher. Pour into tall glasses filled with ice and garnish with the lime slices and a few extra berries.