Add sparkling wine, let foam calm down then add a little more (filling about 1/3 of the glass).
Add fresh grapefruit juice.
Top with club soda.
Garnish the Grapefruit Spritz with edible flowers or a wedge of grapefruit.
Notes
Always taste the Grapefruit Spritzer after you've made it so you can adjust the flavors to suit your tastebuds. You may find that you want more grapefruit flavor.
Don't want to use the flavored champagne? Just use regular. If you like that bitter orange flavor, you can add a few drops of bitters.
You can make a bunch of these at once, quickly, as long as you pre-squeeze the grapefruit juice.
Grapefruit goes well with so many flavors. Consider muddling fresh herbs like basil, rosemary or thyme into the glass before adding ice.
Want to make this Grapefruit Spritzer a little boozier? Add an ounce of gin or vodka!