Cook Lentils: In a medium pot place 1 cup of dried lentils with 3 cups of water, and a pinch of salt. Cook for 15 minutes over medium heat until lentils are tender, once cooked drain off the water and reserve the lentils for later. 

Cook Potatoes: Put peeled potatoes in a large pot and cover with water, bring to a boil and cook until potatoes can be pierced with a fork.

Mash Potatoes: Once cooked, drain and place the potatoes back in the pot. Add the olive oil, milk, salt and pepper. Using a potato masher, mash potatoes until smooth in texture.

Preheat oven to 350 F.

Saute Veggies and Herbs: Over medium heat, saute the chopped mushrooms, onions, garlic, celery, and fresh herbs until soft with 1 tbsp olive oil for roughly about 2-3 minutes.

Add Flour: Once the vegetables are softened, sprinkle 2 tbsp of all purpose flour and stir together.

Add Tomato Paste and Liquids: Add the tomato paste, tamari and vegetable stock, stir well and bring to a simmer.

Add Lentils, Corn and Peas: Mix in the cooked lentils along with the corn and peas. Taste for seasoning and adjust if needed with salt and pepper. Cook for 4-5 minnutes until the sauce thickens slightly.

Layer in Baking Dish: Place lentil mixture into a 9x13in baking dish and top with mashed potatoes. Smooth until you have an even layer of mashed potatoes covering the lentils.

Bake: Place the dish on a baking tray (prevents a mess in case of any spillage) and bake uncovered for 25-30 mins at 350 degrees F. Optional: broil for 1-2 minutes at the end to achieve more browning and crispiness on top.

Cool Briefly: Let cool for 5-10 minutes before serving. The longer it sits, the more it will thicken.