1. Combine first 3 ingredients in a small saucepan. Bring to a boil over medium-high heat, stirring constantly until sugar dissolves. Remove from heat, and cool 30 minutes or until room temperature.
2. Strain basil mixture through a sieve into a large pitcher, discarding basil. Place strawberries and lime juice in a blender; process until smooth. Add strawberry mixture to basil mixture. Gently stir in sparkling water. Serve immediately over ice. Garnish with basil leaves, if desired.