Prepare the Glass: Rim a chilled martini or cocktail glass with sugar. Set it aside.
Combine Ingredients: In a shaker, add vodka, orange liqueur, fresh lemon juice, simple syrup, and limoncello.
Shake: Fill the shaker with ice and shake vigorously until the mixture is well chilled.
Strain: Strain the cocktail into the prepared glass.
Garnish: Twist a strip of lemon peel over the drink to release its oils, then drop it into the glass as a garnish.
Notes
For an extra touch, chill the glass in the freezer for a few minutes before preparing the cocktail. You can also substitute the orange liqueur with triple sec or Cointreau if desired.