In the bottom of a cocktail shaker add 2 blood orange slices, sugar and mint leaf. Using the end of a wooden spoon, muddle the fruit with the sugar and mint.
Once these ingredients are "mashed" add ice and the blood orange juice, agave syrup, whiskey and lemon juice to the cocktail shaker. Shake to mix and strain into a rocks glass filled with ice. Garnish with blood orange slice and serve.