Heat a large deep pan over medium heat. Add the avocado oil and the onion. Saute for 4-5 minutes or until lightly transluscent.
Add the ground beef and season with salt and pepper. Crumble the ground beef until mostly browned. Add the garlic, herbs and frozen vegetables and stir to combine, allowing to cook for another 2 minutes.
Add the tomato paste and stir to cook down for 3 minutes or until a crimson color.
Whisk the arrowroot starch and beef broth and pour into the pan, stirring to scrape up any browned bits from the bottom of the pan. Add the red wine vinegar. Simmer for 5 minutes on low or until thick. Set aside to cool.
To make the crust, combine the cassava flour, gelatin and salt. Whisk well.
Add the palm shortening and use a pastry cutter (or butter knife) to cut the shortening into small pieces into the flour mixture.
Slowly stream in the water while stirring. Add the apple cider vinegar. The crust mixture should still be slightly crumbly.
Grease a 9"x7" pan well (I use this staub oval pan) and add the beef filling. Lightly dust a piece of parchment paper with cassava flour and add the pie dough. Add another peice of parchment paper on top and roll the pie crust out. Place your baking dish on top to use as a guide to ensure your crust in the right shape.
Remove the top layer of parchment paper and carefully flip your crust over the top of your baking dish. Crimp the edges to cover the entire baking dish. Transfer to the fridge for 30 minutes to set.
Preheat the oven to 375 F. Remove the dish from the fridge and score a cross shape in the center to help the crust vent. Brush with egg wash.
Transfer to the preheated oven and bake for 35 minutes or until the crust is golden brown.
Allow to cool for at least 15-20 minutes before serving!