To a medium-sized pot add lentils along with 2 cups of water and bay leaves. Cook over medium heat until lentils turn soft (approx 15-20 mins).
While lentils are cooking, heat up a skillet pan and add some oil or a splash of water. Cook onion, garlic, carrot and celery stalk over medium heat for 5-10 minutes until softened. Take off the stove, drain and set aside to cool down.
In the meantime, toast walnuts in the oven for 5 minutes until slightly roasted.
Place cooked lentils with the rest of the loaf ingredients into the food processor (or a bowl for an immersion blender). Blend until combined.
Place the mass into the greased or layered with parchment paper loaf form.
In a small bowl mix the ingredients for the tomato-maple glaze. Spread on top of the lentil loaf.
Heat up the oven to 200 °C (390 °F) and bake covered with foil for 20 minutes. Then remove the foil and continue baking for another 5 minutes.
Remove from the oven and let cool before transferring the lentil loaf onto a cutting board or a plate.