Preheat oven to 375°F (190°C) and line a baking sheet with parchment paper (if baking).

Make the flax egg: Combine ground flaxseed and water in a small bowl. Let it sit for 5–10 minutes until thickened.

In a skillet, heat a teaspoon of oil over medium heat. Sauté onions for 3–4 minutes until soft. Add garlic and cook for another minute. Remove from heat.

In a food processor, pulse lentils, oats, walnuts, sautéed onion and garlic, tomato paste, soy sauce, herbs, paprika, flax egg, and salt & pepper.

Pulse until the mixture holds together but still has some texture (not a paste).

Roll the mixture into 1.5-inch balls using your hands or a cookie scoop.

Bake: Place on baking sheet, lightly spray with oil, and bake for 25–30 minutes, flipping halfway.

Pan-fry: Heat oil in a skillet and fry meatballs over medium heat, turning to brown all sides (about 10–12 minutes total).

Serve with marinara sauce and pasta, on subs, or with a side of roasted veggies.