Pre-chill a large wine glass in the freezer or with ice water, then discard the ice water.
Fill the glass generously with fresh ice.
Pour 50ml limoncello into the glass.
Add 75ml prosecco, pouring gently down the side of the glass to preserve bubbles.
Top with 30ml soda water.
Give a single brief stir to integrate.
Garnish with an orange slice on the rim and serve immediately.
Add the prosecco before the soda water to protect the wine's carbonation - the lighter soda then sits on top and integrates gently with a single stir rather than being beaten flat by pouring in the wrong order.
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