Preheat oven to 200°C / 400°F / Gas Mark 6. Line a cake or loaf tin with baking parchment.
Cook the lentils in the vegetable stock with half the onion. Once cooked, drain and set aside. (omit this step if ysing ready cooked)
Chop the other half an onion finely. Heat the olive oil in a pan. Then fry the onion and garlic in the oil.
Toast the pumpkin and sunflower seeds (or whatever nuts and seeds you’re using) in a dry frying pan. This should take a few minutes. Keep tossing them to make sure they don’t burn.
Take about two-thirds of the toasted nuts/seeds and roughly chop them in a blender.
In a large bowl put the drained lentils, onion, garlic, seeds, spices, herbs, carrots, nutritional yeast, marmite/vegemite (if using), tomato paste, breadcrumbs and lemon rind. Season with salt and pepper (leave the salt out if using marmite/vegemite). Mix well.
Mix in the linseed/flaxseed mixed with water. Add additional water if the mixture is looking a bit dry. It should hold together nicely and be moist throughout.
Transfer the mixture to the lined tin. Roast for 45 minutes. The topping should be nice and crisp once done.
Serve with roast potatoes, vegetables and gravy.