Spread the 1/4 cup sugar on a small plate, run the lemon wedge around the rim of two glasses, then dip each rim in the sugar and set aside to dry.

Combine the raspberries, 1/3 cup sugar, and 1/3 cup water in a small saucepan over medium heat.

Simmer 5 to 7 minutes, mashing the berries with a spoon, until the syrup turns deep pink and coats the back of a spoon.

Strain the raspberry syrup through a fine mesh sieve into a pitcher, discarding the seeds.

Stir in the lemon juice and the 2 cups cold water.

Taste and add a little more sugar if the lemons were especially tart.

Fill the sugar-rimmed glasses with ice, carefully pouring in the lemonade without disturbing the rim.

Garnish each with a raspberry and a lemon slice on the rim, then serve.