Cover the potatoes in a large pot with water and bring to a boil. Cook for about 15-20 minutes until the potatoes are fork tender. Strain and mash with a little bit of milk, ½ tsp garlic powder, and a pinch of salt until you reach mashed potato consistency. Set aside.
Preheat the oven to 400 degrees fahrenheit and lightly grease a 9x9 baking dish.
Heat a large skillet over medium high heat and add the avocado oil. Add the onion and saute for about 3 minutes until fragrant. Add the garlic and cook for another minute.
Add the ground beef and pinch of salt and pepper and cook for about 5-7 minutes until cooked through.
Add the tomato paste, coconut aminos, and apple cider vinegar and mix.
Add the mixed vegetables and bone broth and cook for about 5 minutes, stirring until the vegetables are thawed completely.
Add the arrowroot mixture, salt, and a bit of black pepper. Stir to combine. Bring to a simmer and allow to thicken for 5 minutes. Adjust seasonings as needed.
Pour the beef mixture into the baking dish and spread evenly. Distribute the potato mixture over the top of the beef and spread evenly. Cook for about 15-20 minutes until the edges are bubbling.