To make the infusions:
Lightly crush 1 tablespoon pink peppercorns in a mortar and pestle, or with a heavy rolling pin.
Add 1/2 tablespoon crushed peppercorns to a small glass jar with a lid, then pour 2 1/2 ounces London Dry gin on top. Close the jar and gently shake.
Repeat with remaining 1/2 tablespoon crushed peppercorns and 2 1/2 ounces Campari in a separate jar.
Let sit for 24 hours, shaking occasionally.
Line a funnel with cheesecloth and place funnel above a clean glass container. Pour gin/peppercorn mixture into funnel and let the gin completely drain into the container.
Repeat with the Campari/peppercorn mixture, in a separate container.
To garnish the drinking glasses:
Lightly crush 1/2 tablespoon pink peppercorns in a mortar and pestle, or with a heavy rolling pin.
Pour a small amount of simple syrup (or maple syrup) on a plate. Place a pile of crushed peppercorns on a different plate.
Dip one part of the rim of a rocks glass into the syrup and then into the crushed peppercorns so they stick to the glass. Repeat with the other glass. Set aside.
To make the cocktail:
In a mixing glass (or pint glass), combine 1 ounce infused gin, 1 ounce infused Campari, and 1 ounce sweet vermouth. Add several ice cubes and stir to chill - approximately 30 rotations.
Add a large ice block to prepared rocks glass. Strain contents of mixing glass over ice block.
Repeat to make a second cocktail.
Make one cocktail at a time to ensure that they are equal. The peppercorn garnish is for aroma only. It's not recommended to drink from the garnished part of the glass.
The peppercorns in the infusion will absorb some of the gin and Campari, so always use a bit more liquid than you need for the final drink recipe.