Blackberry-Lime Margarita

Why I Love This Recipe
This recipe originally came from Gourmet Magazine, but I got it from www.gluten-freegirl webpage && it look interesting & similar to my (Berry)3 Margarita recipe.
Ingredients You'll Need
2 cups (~11oz) blackberries
2 cups ice
1/2 cup fresh lime juice
3/4 cup white Tequila
1/4 cup sugar
Directions
In a blender puree blackberries.
Force puree through a fine sieve into a small bowl and discard solids.
In a cocktail shaker combine 1/2 cup puree and remaining ingredients and shake well.
Strain drink into 4 stemmed glasses.