Preheat the oven to 200°C. Lightly oil a baking sheet or an oven-safe skillet.
Heat 1 tablespoon of olive oil in a medium skillet over medium heat. Add the onion and sauté for 5 minutes until soft and translucent. Add 2 cloves of minced garlic and continue sautéing for another minute until fragrant. Remove from heat.
Place the rolled oats in a food processor and process until they reach a powdery consistency. Add the remaining clove of garlic, cooked lentils, tomato paste, tamari sauce, red wine vinegar, oregano, thyme, basil, chilli flakes, salt and black pepper to the food processor, pulse a few times until combined but still retaining some texture. Be careful not to over-process the mixture, it should not be smooth.
Taste the mixture and adjust the seasoning if needed. Now roll the mixture into walnut-sized balls (this mixture should make around 24 balls).
Arrange the balls on the prepared baking sheet and brush or spray them with the remaining tablespoon of olive oil. Place in the hot oven to bake for about 24 minutes, flipping halfway through, until the balls are firm and lightly browned.
Serve the lentil meatballs with your favorite sauce.