Combine all ingredients in a cocktail shaker (you could also use a mason jar with a screw-on lid!)
Fill the shaker 3/4 with ice and shake until chilled, about 12 seconds.
Strain the liquid into a rocks glass filled with ice.
Garnish with seasonal edible flowers, if desired. I used apple blossom and lilacs from my yard for their beautiful aromas.
Notes
Simple Syrup vs. Pineapple Ginger SyrupFind my pineapple ginger syrup recipe here. While the original Starbucks drink ingredients lists pineapple ginger syrup, after a bunch of recipe testing, I found that this homemade version tasted just like the original even when using basic simple syrup.In my opinion, the pineapple ginger flavor is not very prominent in the Starbucks Guava Passion Fruit Drink, so if you don’t have pineapple juice, ginger juice, or fresh ginger root, feel free to make a standard 1:1 simple syrup and use that instead!Simple Syrup
½ cup sugar
½ cup water
Combine the sugar and water in a jar or other sealable container and stir until all of the sugar has dissolved, about 2 minutes. Store any leftover syrup in a closed container in the refrigerator for up to 2 weeks. For an even speedier syrup, use hot water.Note: there is no need to boil your simple syrup, and doing so is actually not recommended for making consistent syrups (and consistent drinks!). Boiling the simple syrup will burn off some of the water, which will mean a sweeter syrup.