Line two rimmed baking sheets with parchment paper or foil, and preheat the oven to 375°F
Finely mince the mushrooms, shallot, sweet potato, and cilantro
In a large bowl, combine the ground beef, fish sauce, tomato paste, and the minced veggies and herbs. Sprinkle on salt and pepper and incorporate
Scoop out meatballs roughly 1½ tablespoons in diameters and place on baking sheet
Bake each tray of meatballs for 15 to 20 minutes, rotating the tray at the midpoint to ensure even cooking.
Plate and serve immediately, or store in an airtight container in the fridge for up to three days. You can also freeze the cooked meatballs for up to 6 months. Simply freeze them in a single layer and then place the solid orbs in a freezer bag or sealed container.