How to Make It
Place strawberries and sugar in a small saucepan; muddle using a wooden spoon. Cook mixture over low, stirring occasionally, until sugar melts, about 5 minutes.
Place each peppermint sprig in the palm of your hand. Give it a good slap (this brings out the volatile oils). Stir peppermint sprigs into strawberry mixture; remove from heat. Let to cool to room temperature, about 15 minutes.
Remove and discard peppermint sprigs from strawberry mixture. Pour mixture through a fine mesh strainer into a half-gallon pitcher. Stir in sparkling water.
Fill 6 highball glasses with ice; pour strawberry mixture evenly into glasses. Slice a small slit in each of the whole strawberries; garnish each glass rim with 1 strawberry.