Add 1 tablespoon oil or fat to a large stock pot, and warm over medium heat. Add onions and stir to combine. Cook until onions are softened and translucent, about 10 minutes. Stir occasionally to prevent browning.

Add minced garlic and fish sauce, and stir constantly until fragrant and softened, about 1 minute.

Add second tablespoon of oil or fat along with all mushrooms, and stir to combine. Cook, stirring occasionally, until mushrooms are soft, another 6-8 minutes.

Add broth and coconut milk, then bring to a simmer. Reduce heat, cover, and let simmer 10-15 minutes while you prepare the meatballs.

Remove cover and turn off heat. Using an immersion blender (or transfer to a blender) carefully purée sauce until smooth. Adjust seasonings to taste and add more liquid if needed.

Preheat oven to 400 degrees F. Line a large baking sheet with parchment paper and set aside.

Add ground meat and all ingredients to a large bowl. Use your hands to incorporate mixture, then form into golf ball sized meatballs, making about 8 total. Place each meatball on sheet pan and set aside.

Bake meatballs in preheated oven for 20-25 minutes, or until lightly browned and cooked through.

While your meatballs are baking, prepare noodles according to the package instructions.

Add cooked noodles to a plate, toss with desired amount of sauce, and top with meatballs. Garnish with sesame seeds, cilantro, sliced green scallions, and hot sauce if desired.