Cook Lentils: Rinse and cook lentils according to package directions. Drain. If you don't have instructions, bring 2 cups of water to a boil in a medium sauce pan. Add the lentils, cover and simmer lightly for 15-20 minutes until tender. Drain off any excess water and set aside.

Prepare to Bake: Preheat oven to 350 and line a baking sheet with parchment paper.

Cook Mushrooms: Add olive oil to a saucepan and cook the diced mushrooms over low to medium heat until they have released all moisture and turn golden (about 15 minutes). Stir often to prevent burning.

Blend Ingredients: Add the remaining ingredients except for the oat flour to a food processor. 

Add Lentils and Mushrooms: Once mushrooms and lentils are cooked, add to food processor as well. Pulse several times until it resembles ground meat. Avoid overblending into a paste. Some whole lentils and larger pieces of mushroom should remain for texture.

Mix with Oat Flour: Transfer mixture to a large mixing bowl and stir in the oat flour very well. Let rest for 10 minutes for flour to absorb moisture.

Roll Meatballs: Roll into balls a bit larger than a golf ball and spread out on baking sheet. You should get 12-15 meatballs. Mist with a light coating of olive oil cooking spray or use an oil mister to spray with a light mist of any cooking oil.

Bake: Bake for 20-25 minutes, rotating the tray after 10 minutes, until they are firm and golden brown.

Serve: Serve with your favourite tomato-based sauce and/or pasta of choice, gravy, on a meatball sub or any other way you'd enjoy meatballs.