Spread the almonds on a baking sheet and toast for 8 minutes. Set the almonds aside on a plate to cool before grinding them to a fine meal in a mortar, food processor, or clean coffee mill.

In a bowl, combine the butter and maple syrup. Allow the mixture to cool slightly, then add the almond meal, flour, and salt. Stir well to combine.

Press the dough into the tart pan with moistened fingertips. Use your thumbs to press the dough into the fluted sides of the pan. There will be just enough dough to completely fill the pan. Prick the dough several times with a fork.

Bake for 20 minutes, or until golden brown. Transfer the tart shell to a rack to cool. Turn the oven off.

To make the filling, in a saucepan over medium heat, combine the coconut milk, 1 cup of the water, sugar, agar, and turmeric and simmer until the agar dissolves. Stir in the lemon juice, lemon zest, and vanilla. Raise the heat and bring to a boil.

Dissolve the arrowroot in 1/2 cup water, then stir into the saucepan and cook for 1 minute, or until the mixture thickens. Remove the pan from the heat and whisk in the yogurt until the mixture is creamy smooth. Pour the filling into the tart shell and cool at room temperature before refrigerating until firm and chilled, about 1 to 2 hours.