In a medium-sized pot, sauté the onion in 3 tbsp water until translucent on medium heat (add more water if necessary). Add in garlic and sauté for additional 2-3 minutes.
Add in lentils and 1.5 cup water. Bring to a boil then let simmer for 15-20 minutes (until liquid is absorbed and lentils are tender.)
In a separate skillet, sauté mushrooms in 3 tbsp water on medium heat for about 5 minutes.
Blend oats in a food processor (or a blender) to create oat flour.
To the food processor, add in the mushrooms, lentils, parsley, allspice, nutmeg, pepper, soy sauce, and Worcestershire sauce.
Process until everything is combined. Don't process until it's total mush - some texture from the lentils and mushrooms should still be there.
Add more soy sauce (or salt) and pepper if needed.
Let the mixture sit for about 15 minutes. It will become thicker and easy to roll.
Pre-heat oven to 425F degrees.
Cover a baking sheet with parchment paper or a silicone baking mat.
Roll into meatballs and place onto baking sheet. Spray with some cooking oil if desired. Bake for 20-25 minutes, flipping halfway.
Gravy
In a medium-sized pot, add in all gravy ingredients EXCEPT for the cornstarch and water.
Bring to a simmer on medium heat, stirring occasionally. Remove from heat.
In a small bowl, whisk together the cornstarch and water to create a cornstarch slurry. Whisk the cornstarch mixture into the gravy.
Return the pot to the burner and bring to a simmer again. The sauce should be nice and thick. If it's too thin, add a little more cornstarch slurry.
Pour the gravy over the meatballs. Eat as is, or serve with pasta or mashed potatoes.
Notes
This recipe makes about 20 meatballs if measured at 1.5 tbsp each.If you can't find vegan Worcestershire sauce, you can substitute more soy sauce and a dash of apple cider vinegar.