Add lentils to a saucepan. Add the water. Bring this to a boil, then reduce heat to low, cover, and cook for 25 minutes.
When the lentils are done (they should be tender), drain any excess liquid using a strainer.
For the Meatball Mix:
As the lentils are cooking, add oil to a skillet over medium heat. Cook until it's shimmering, then add the chopped onions. Cook until translucent, approximately 5 minutes. Then add garlic and cook for one minute.
Stir in the chopped walnuts, bouillon, and Worcestershire sauce until combined. Then add the ground flax, oats, seasonings, and yeast flakes. Stir until combined.
Add the cooked and drained lentils while they're still hot. Use a rubber spatula to stir the meatball mix throughout the lentils. Then either use the spatula or a potato masher to press the lentils. You want to leave some of the lentils whole for texture, but mashing a good part of it.
Test the batter. If it stays together when you press it between your fingers, then it's good to go. But if it's dry, stir in a tablespoon or two of water. Here is where you can also add more salt and pepper to taste.
Once the batter is ready, roll it into 1-inch balls.
For Cooking Meatballs:
Skillet Method: Spray cooking spray over a skillet. Place over medium to medium-high heat. Place meatballs in the skillet, leaving a little space between them. Sprinkle the tops of each with freshly ground pepper. Cook for several minutes until the bottom side is golden brown. Use tongs to turn them and cook the other side as well. Place cooked meatballs in a heated oven or toaster oven set at 250°F/120°C while repeating this process with the rest of the lentil batter.
Oven Method: Heat your oven to 375°F/190°C. Line a baking sheet with parchment paper. Place meatballs equally spaced apart on the baking sheets. Give them a light coating of vegetable cooking spray. Sprinkle the tops of each with freshly ground pepper. Bake for 20 minutes, using tongs to flip them half-way through.
Serving suggestions: Serve lentil meatballs in sauce like marinara sauce or BBQ sauce. Use it to create a plant-based spaghetti and meatballs dish or a vegan meatball sub sandwich. It's great to serve a few on salads, too.
Transfer meatballs to an airtight container where they will last 4 to 5 days in the fridge. Place them in a freezer-safe container where they will keep for 2 months in the freezer.
Notes
You can substitute soy sauce for the bouillon and/or the vegan Worcestershire sauce.If using rolled or old-fashioned oats, I recommend running them through a food processor first to break them down. This helps them to become a similar texture to instant oats and they will be more absorbent.