Lime cashew cream:
1Preheat oven to 350˚F
2Pulse together all ingredients until they come together in a ball in a food processor. (I did this in the Blendtec Twister Jar attachment)
3Press crust into tart pan and up sides evenly using fingers. Prick crust with a fork all over. Bake for 10 minutes at 350˚F on a baking sheet (for easy maneuverability) on the middle rack.
4Remove crust from oven and let cool to room temp in tart pan on a cooling rack.
1Wash and trim ends of rhubarb. Create rhubarb ribbons using a vegetable peeler or mandolin slicer to thinly slice rhubarb stalks lengthwise. You will need about 24 rhubarb ribbons for the lattice top. Save the remaining rhubarb for the gelée.
2Bring water and maple syrup to a rolling simmer in a saucepan.
3Roll rhubarb ribbons up and working in batches, blanch them in the maple syrup-water reduction for about 30 seconds to 1 minute. Transfer rhubarb ribbons to a towel lined baking sheet using kitchen thongs and allow them to drain while you blanch the next batch. Carefully unroll the ribbons.
4Create a lattice or basket-weave pattern by weaving the rhubarb ribbons over and under each other on top of a sheet of wax paper.
5Use the tart pan as template to cut away the edges of the lattice with a sharp knife, creating a 9" round circle which will lay on top of the finished tart. Save the rhubarb trimmings for the gelée.
6Chop the uncooked rhubarb pieces. Reduce the rhubarb cooking liquid at a low boil and add the raw rhubarb and lattice trimmings to the liquid, simmering until tender, about 1 minute.
7Transfer rhubarb and cooking liquid to a blender. Add strawberries, lime zest, agar agar, and vanilla extract and purée until smooth. Return purée to the saucepan and cook on medium heat, stirring constantly for 5 minutes to activate the agar agar. Strain warm gelée through a fine sieve to remove any lumps that may have formed from the agar agar. The gelée will continue to thicken and set as it cools.
8Pour gelée into cooled tart crust and spread into a even layer with an offset spatula.
9Transfer the tart to the freezer to allow the gelée layer set up while cashew cream is prepared.
Lime cashew cream:
1Drain and rinse cashews. Add all ingredients to a blender and purée until silky smooth.
2Spread cashew cream over set rhubarb gelée layer.
3Transfer rhubarb lattice to top of tart by inverting it using the wax paper and then peeling away the wax paper.
4Brush the top of the rhubarb lattice with a bit of maple syrup and lime juice mixed together for a glossy sheen.
5Freeze tart until solid to set the cashew cream layer.
6When ready to serve, remove tart from freezer and allow it to sit at room temperature for 10 minutes before cutting. Use a sharp knife with a quick stroke to cut through the lattice layer with ease.
7Keep leftover tart in freezer, wrapped to keep fresh. The tart will keep frozen for several months.