Preheat your oven to 200°C fan (220°C conventional, gas 7). Roughly chop the potatoes (no need to peel them) and boil for 12 minutes until soft.
Finely dice the onion and carrots and crush the garlic.
Heat a glug of olive oil in a large pan and fry the onion, garlic, carrots, oregano and bay leaves for 5 minutes until the onion and carrots soften.
Add the peas, sweetcorn, tamari, gravy granules, drained lentils and tinned tomatoes and mix. Simmer for 5 minutes to thicken, then remove the bay leaves.
Drain the potatoes, put them back in the pan with the butter, milk and a generous pinch of salt and pepper and mash.
Spoon the lentil filling into a large baking dish and top with the mash. Bake for 30 minutes until golden.
Notes
Step-by-Step Photos: My blog post includes step-by-step photos to help guide you through making this recipe.Substitutions and Variations: I have included a list of these in the post above.Gluten Free and Dairy Free: Choose gravy granules labelled gluten free (many contain wheat), and use dairy free butter and an unsweetened dairy free milk.To Store: Cool quickly and keep in an airtight container in the fridge for up to 2 days. Reheat once until piping hot.Make Ahead: Assemble the pie, cover and keep it in the fridge for up to 2 days, then bake for about 40 minutes until piping hot.To Freeze: Freeze before or after baking for up to 3 months. Defrost in the fridge overnight, then bake or reheat once until piping hot.Tip 1: If you use a larger dish, you may need more mash to cover the top.Tip 2: There are a lot of vegetables, so chop them before you start.Tip 3: Two 400g tins of lentils give about 530g drained. You can use beef mince in place of the lentils if you are not vegetarian, or add tofu.