Make the 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.
Prepare the TVP: Marinade TVP in the vegan Worcestershire Sauce with enough water to cover the dry TVP. Stir and let sit until rehydrated and the flavours are absorbed, 1 hour to overnight.
Prepare the lentils: 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. Set aside
Preheat oven to 350°F. Lightly grease a 2 quart casserole or deep baking dish. Set aside.
Make 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 organic canola oil in a large, deep skillet over medium heat. Add the onion. Stir fry until slightly browned, aromatic and soft. Add the celery, carrot, Italian seasonings, and seasoning. Stir until well mixed. Add the garlic and stir for about 30 seconds.
To the pan, add the tomato paste, the vegetable stock and let mixture simmer for 2-3 minutes or until vegetables are cooked and slightly softened.
Add the lentils and TVP. Stir well and cover. Let simmer for 2-3 minutes or until liquid in mostly absorbed. Remove from heat.
Add the frozen peas to the mixture. Stir until well combined.
Spoon filling into the prepared casserole. Smooth top of mixture with a spatula.
Spoon the mashed potato on top of the filling and smooth out with a spatula so it completely covers the filling.
Place on a cooking sheet in the oven (to prevent spills in case the filling boils over) Bake, uncovered, for 25 – 30 minutes.
Let cool for 15 minutes before serving.