Chop the sweet potatoes into rounds that are about 2 inches thick and place them in a pot. Fill the pot with water, then bring it to a boil over medium-high heat. Boil the potatoes until very soft when poked with a fork, about 20 to 30 minutes. Note: you can prepare the rest of the recipe while the potatoes are cooking.
Once the potatoes are cooked, drain the water and allow them to cool enough to handle. Once cool, remove the skins from the potatoes and mash them until creamy. Set aside.
Preheat the oven to 400 degrees F (200 degrees C).
Add the avocado oil to a large non-stick skillet over medium heat. Once hot, add the chopped onion and sauté, stirring occasionally, until the onion begins to brown, about 5 to 8 minutes.
Move the onions off to one side of the skillet and add the ground meat, leaving it in its square hunk form. Allow the meat to brown on one side for 2 to 3 minutes, then flip it to the other side and brown for another 2 to 3 minutes. Use a spatula to break up the meat into smaller chunks and stir well.
Add the carrots, garlic, vinegar, liquid aminos, and water. Cover the skillet with a lid for a few minutes to allow the mixture to cook and flavors to meld.
Remove the lid and stir in the peas, spinach, and sea salt. Continue cooking uncovered for a few minutes to allow the sauce around the solids to thicken slightly.
Transfer the meat and vegetable mixture to a large casserole dish. Spread the creamy mashed sweet potatoes over the meat mixture, making sure to cover it evenly.
Bake in the preheated oven for 30 minutes, or until everything is hot and slightly bubbly. The top should be golden and inviting.
Once done, remove from the oven and allow it to cool for a few minutes before serving. Enjoy your homemade Easy Shepherds Pie with Sweet Potatoes!