Chill 4 julep or old-fashioned glasses in the freezer until frosty; at least 30 minutes.
Strain the chilled simple syrup with a fine mesh sieve (see Chef’s Tips) into an airtight container.
Add 1 tablespoon (15 ml) of the mint simple syrup to each chilled glass. For a sweeter drink, add 2 tablespoons (30 ml).
If using, place 3 mint leaves in the bottom of each glass. Using a muddler or the end of a wooden spoon, gently tap the mint to bruise the leaves; do not pound or tear the leaves, as they will blacken and discolour.
Fill each glass halfway with crushed ice. Add ¼ cup (63 ml) of unsweetened pear juice and 1 tablespoon, and 1 teaspoon (20 ml) of lime juice to each glass. Stir with a cocktail stirrer (or long-handled spoon) to thoroughly combine the liquids and to keep the glass cold. Top the glasses with more crushed ice.
Garnish with fresh mint and a cocktail stirrer. Stir before enjoying.