Add 2 tbs (about 1.5 fl oz) London dry gin, 1 tbs bergamot liqueur, 3/4 tbs fresh lemon juice, 1/2 tbs simple syrup, and the optional 1/2 egg white into a cocktail shaker (without ice).

Dry shake

Seal the shaker and shake vigorously for 10–15 seconds to emulsify the egg white and fully integrate flavors. This creates a silky foam.

Add ice & shake

Open the shaker, add a generous handful of ice (about 1 cup). Shake again hard for 10–15 seconds until the shaker is cold to the touch and well-chilled.

Double strain

Fine-strain the cocktail into a chilled highball or Collins glass filled halfway with fresh ice. Use a fine strainer in addition to the shaker strainer if you used egg white to remove small ice shards and foam bits.

Brightener & Top

Top the strained cocktail with 1.5 oz club soda (or sparkling water). Pour gently to preserve the foam and maintain a light effervescence.

Express the bergamot zest (or orange zest) over the drink by holding it skin-side down above the glass and giving a quick pinch to release the oils. Rub the zest around the rim and drop it into the glass as garnish. If using a thin bergamot slice, float it on top.

Serve

Serve immediately while effervescent. Sip to enjoy the bright citrus bergamot notes balanced by juniper from the gin and the silky texture from the egg white (if used).

If avoiding raw egg, omit egg white and increase shaking time with ice to produce chill and slight dilution; the cocktail will be slightly less silky but still balanced.