- Combine ingredients in a cocktail shaker and muddle thoroughly. You can also use a blender to quickly juice and combine the ingredients.
- Add ice and seal the cocktail shaker. Shake for 30 seconds.
- Double strain using a fine-mesh strainer into a margarita or coupe glass (any stemmed or even short glass will do). The double strain ensures the cocktail does not have a smoothie-like texture and is refreshing but not heavy to drink.
- Garnish with a slice of watermelon and basil flower (optional).