Rim the ridge of your glass with a lime wedge and dip in a mix of margarita salt + sugar [I used about 3 tablespoons salt to 2 teaspoons sugar]. Fill the glass with ice. In a cocktail shaker, combine tequila, grand marnier, simple syrup and lime juice with ice, and shake for about 30 seconds. Pour over ice and squeeze in lime slices, then drop in blueberries and more fresh basil leaves.
For roasted blueberry basil simple syrup:
Preheat oven 400 degrees F. Place 1 cup of blueberries on a nonstick baking sheet with a pinch of salt. Place in the oven and roast for 15-20 minutes, or until berries start to burst.
While blueberries are roasting, combine equal parts sugar and water (such as 1/2 cup of each) in a small saucepan and add 6-8 fresh basil leaves, bring to a boil and let sugar dissolve, then turn off heat and let cool completely, about 20 minutes. Combine 1/2 cup simple syrup + roasted blueberries in a blender/food processor and blend until combined. Feel free to strain if you don’t want small blueberries chunks. I love them!
This recipe can be easily doubled, quadrupled, etc. Since everyone’s tastes differ, add simple syrup 1/4 cup at a time and go from taste. I also suggest buying the lime juice if you plan on making a pitcher (or 2) considering you’d have to squeeze a billion limes to get enough juice.