Preheat the oven to 350°F. Combine walnuts, buckwheat flour, coconut oil, & salt in a food processor and process until a crumbly mixture forms. Transfer to a 9” tart pan (pie pan will work as well). Pack the crust tightly using the back of a measuring cup. Bake in the oven for 15 minutes. Once it’s done let it cool before adding the filling. 

Add the mandarin juice, coconut cream, cornstarch, granulated sugar, and mandarin zest to a medium saucepan. Mix evenly. Bring to medium-high heat for 7 minutes or so while whisking continuously. The mixture will thicken enough to coat the back of a spatula. Use a handheld blender/mixer if lumps form.

Pour the tart mixture into the cooled crust, smooth the top, and let the tart set for 3 hours in the fridge. Wait to garnish after the tart has set. Serve and enjoy!