To make simple syrup: Take equal parts sugar and water, bring to a boil over medium-high heat, stirring to dissolve the sugar, about 3 minutes. Remove, cool and refrigerate in a tightly sealed jar. It will keep for about 3 months. This is a totally optional addition. Most of the time the grapefruit juice is plenty.
Drop 3 medium torn basil leaves into a cocktail shaker, fill will ice. Add 1.5 ounces of freshly squeezed grapefruit juice, 1.5 ounces vodka, .5 ounce of Villa Cappelli EVOO, and .25 ounce simple syrup. Shake VIGOROUSLY for at LEAST 10 seconds if not 30.
If you are making a bigger batch, remember the ratio: equal parts vodka to grapefruit juice, then half that in EVOO, then a quarter simple syrup.
Strain into your glass and garnish with a small basil leaf.