remove rind from 2 medium sized limes
quarter limes and put in blender
add 4 jiggers Sarpa di Poli grappa
add 1 (to 2) teaspoons lemon juice
blend on high until mixed
strain mixture, pressing liquid out of pulp
return fluid to blender and add 2-3 jiggers sugar syrup (1/4c. water, 1/2c. sugar heated on stove to mix then cooled) and 8-10 ice cubes
blend until smooth, serve in martini glasses with bitters