Step 1.
- Muddle fresh basil leaves in a large bowl to release their aroma.
Step 2.
- Add gin, lemon juice, and simple syrup to the bowl with the muddled basil.
Step 3.
- Pour in the tonic water and gently stir to combine all ingredients.
Step 4.
- Fill with ice and stir again for even chilling.
Step 5.
- Serve in cups or glasses, garnishing each with a sprig of basil.