Modified from this recipe
1.5 ounces tequila
1 ounce Cointreau
1/2 tbsp sugar
1 lime (just the juice)
1/4 cup sparkling water
Put all of the ingredients into a shaker.
Mash the blackberries with everything until they are pulp.
Making sure the top is secure, shake everything up.
Pour over ice and enjoy.
Note: You can strain out the blackberry mash if you don’t prefer pulp.