Preparing the filling: Place lentils in a large pot filled with water. Bring to a boil over high heat. Let cook for 15-20 minutes until well cooked. Drain well and place in a large mixing bowl.
Cook TVP or soy granules according to package instructions. If buying in bulk without instructions, soak the TVP for 1 hour.
Once soaked. place it in a pot covered with water. Boil for 10-20 minutes until spongey and rehydrated. Drain and spoon into the large mixing bowl with the lentils.
Add the vegan Worcestershire sauce, stir well to mix and let sit for 1 hour.
Make mashed potatoes: Cut potatoes into medium small cubes. Place in a large pot and cover with water. Bring pot to a boil over medium high heat. Let potatoes boil until tender, about 15 minutes.
Remove from heat and drain well in a colander or sieve. Place potatoes back into the pot. Add the soy milk, butter, pepper and cheese. Stir well until mixed. Set aside.
Making the Shepherd's pie: Prepare the vegetables. Chop the onion. Mince the garlic. Dice the carrots and celery. Set aside in separate bowls.
Heat the canola oil in a large, deep skillet over medium high heat. Add the onion and garlic. Stir fry them until slightly brown and soft. Add the celery, carrot, Italian seasonings, and seasoning. Add the vegetable stock and let simmer for 2-3 minutes or until vegetables are cooked and slightly softened.
Add the tomato paste. Add the lentils and TVP. Stir well and cover. Let simmer for 2-3 minutes or until liquid in mostly absorbed.
Spoon filling into a large 9x9 or 13 x9 baking dish.
Spoon the mashed potato on top of the filling and smooth out with a spatula so it covers the filling.
Place on a cooking sheet in the oven ( in case it boils over) and bake, uncovered, for 25 – 30 minutes.