Cook the Lentils: Rinse lentils under cold water. Combine with water in a saucepan, boil, then simmer for 20 minutes until tender. Drain and cool slightly.

Sauté the Aromatics: Heat oil in a skillet, add diced onion and sauté until translucent. Stir in minced garlic and chopped mushrooms, cooking until tender.

Prepare the Meatball Mixture: Pulse rolled oats in a food processor. Add cooked lentils, sautéed mixture, parsley, soy sauce, salt, and pepper. Process gently until combined.

Let the Mixture Rest: Transfer mixture to a bowl and rest for 10 minutes at room temperature.

Preheat the Oven and Form Meatballs: Preheat oven to 350°F. Roll lentil mixture into balls and place on a parchment-lined baking sheet.

Bake the Meatballs: Brush tops lightly with oil and bake for 25-30 minutes, flipping halfway through.

Make the Gravy: Combine vegetable broth, coconut milk, Dijon mustard, garlic powder, and onion powder in a saucepan. Bring to a boil.

Thicken the Gravy: Mix cornstarch with cold water and add to boiling gravy. Reduce heat and simmer until thickened.

Serve and Enjoy: Serve meatballs drizzled with gravy, paired with pasta, rice, or mashed potatoes.