In an ice-filled cocktail shaker, combine 1 ½ oz. lemon-flavored vodka, 2 oz. fresh orange juice, ½ oz. fresh lemon juice, and ½ oz. simple syrup. Shake well. Then strain into a goblet over ice. Gently add 1 oz. fresh blackberry juice (strained, pureed berries) in a thin, steady stream. Garnish with an orange slice.