Preheat oven to 180 degrees celsius. Grease a rectangle tart tin (13.5" inch). Set aside.
In a food processor, combine crust ingredients and pulse to combined. You should get a moist mixture than can be easily moulded.
Bake for 15 minutes until crust is golden brown. Transfer to a wire rack and let it cool while you're preparing the filling.
Place oat milk, coconut milk in a saucepan over medium heat and bring to a simmer. Turn off the heat then add 3 of the Earl Grey teabags and leave to brew, covered, for 15 minutes. Remove the teabags and squeeze out all the liquid.
Bring earl grey milk to the boil then whisk in agar agar, vanilla and cornstarch. Whisk until agar is dissolved. Then add in lemon juice, maple syrup, whisking constantly. Allow to boil for approximately 30 seconds.
Pour the mixture into cooled tart. Place tart in the fridge to set, about 4 hours or overnight. Garnish tart as desired with fruits and enjoy!