Add guavas to a large heavy-bottomed pot with ¾ cup water and lime zest. Bring to a boil over medium-high heat, reduce heat to medium-low, and simmer, stirring occasionally, until the fruit is soft. Use a wooden spoon or potato masher to break up the fruit as it cooks. Pass guava through a fine mesh strainer into a clean bowl, and set aside.

Scoop the passion fruit flesh, juice and seeds into a fine mesh strainer, and using a spoon, stir to pass the juice and flesh through the strainer. Discard the seeds and anything that clings to them. At this point you should have about 1 cup of guava puree and 1/3 cup passion fruit puree. Combine both purees in one bowl and add sugar to taste (I added 2 tablespoons). Store purée in the fridge covered until you are ready to use. You’ll have enough to make 5 - 6 drinks.

To make the cocktail, combine fruit puree with tequila, simple syrup and lime juice in a short glass with ice, and stir to combine and chill. Garnish with a lime wedge.