Place strawberries, basil, lime juice, and sugar into a mason jar or a glass.
Using a muddler or the back of a spoon muddle or mash the strawberries
Strain the mixture through a small strainer.
Add ice to two medium-sized glasses.
Add 1.5 ounces of gin to each glass.
Divide the strained strawberry basil lime juice between the two glasses.
Top with tonic water.
Garnish with strawberries, basil, and lime slices.