Slice the fruit if necessary and divide it among four individual shallow serving bowls. Fill a large (4-quart) saucepan with 1 inch of water and set it over medium-high heat.
In a stainless steel bowl big enough to rest at least half way into the saucepan, whisk together the egg yolks, sugar, juices, tequila and lime zest.
When the water reaches a boil, lower the heat so it is at a low simmer. Nestle the bowl into the saucepan. Whisk the yolk mixture continuously, until it becomes thick and fluffy, about 3 minutes. Remove the bowl from the saucepan. Drape a few spoonfuls of the warm “espuma” over the fruit in each bowl and serve immediately with something crunchy and sweet crumbled on top.