Whisk together sunflower seed meal, shredded coconut, powdered monk fruit sweetener, and salt. Add melted butter, egg, vanilla extract then whisk again.
Transfer the crust mixture to a baking pan and press it into an even layer. Bake until the edges of the crust are golden brown.
Mix powdered monk fruit sweetener, sunflower seed meal, eggs, lemon, juice, and lemon zest. Allow the bowl to sit for a minute to see if any egg floats to the top and appears to be un-mixed. If so, mix again until eggs are fully incorporated.
Remove the baked crust from the oven and place the pan in the center of large baking sheet. Pour the lemon filling on top of the crust, then pour enough water into baking sheet to fill it up ~1/2 inch. Bake until the filling has set.
Turn the oven off and then crack the oven door open and allow the pan to sit in the cooling oven for 1 hour before removing the pan from the oven.
Transfer the pan to the refrigerator to chill uncovered before slicing into 16 bars.