Traditional key lime pie is silky smooth, creamy, and rich, and so is this one. But would you believe that avocados are the star of the show here? Since they are a vivid green, I thought that flavouring avocados with fresh lime to become a tart filling would be just the ticket. Bingo: all the creamy qualities of avocados with the sweet-tart charm of citrus. The recipe for the filling is merely a guide, so adjust the amounts of sweetness and sourness to your liking.
Make the crust: Pulse the nuts in a food processor until chunky. Add the coconut, dates, and salt, and continue to pulse until the nuts and dates form a solid mass when squeezed together.
Line a 6-cup muffin tin with plastic wrap. Divide the crust mixture into 6 golf-ball-size portions and press one into each muffin cup, pressing up the sides as well, to create a tart shell.
Put the muffin tin in the freezer to let the crusts harden for at least 1 hour.
When you are ready to fill the tart shells, pull up the edges of the plastic wrap to remove the tart shells from the muffin tin.
Make the filling: Put the avocados, maple syrup, coconut oil, lime juice, and salt in a food processor and blend on the highest setting until smooth. Taste for sweetness and add more sweetener if necessary. If the avocados are overripe, add more lime juice to taste.
Spoon the filling into the tart shells and sprinkle the lime zest on top. Return to the muffin tin for storing and put in the freezer for at least 2 hours.
Remove the tarts from the freezer 15 to 20 minutes before serving.