Cook your brown rice as per your preferred method. I boil mine in plenty of water because I am too chaotic for the absorption method. Strain and set aside.
Preheat your oven to 200C/400F.
Place the oil in a large pan or skillet over a medium heat. Once warmed, add the leek and herbs and cook until softened and fragrant. Add the mushrooms and cook until they are shrivelled and soft. You can allow them to brown a little for extra flavour, if you like.
Combine the ingredients for the blended mixture in your high-speed food processor (I use a Nutribullet). See the notes in the body of the post about using half the tofu crumbled in the mixture as an option. Taste and adjust according to your preferences.
Place the rice and cooked leek mushroom mixture in a large mixing bowl. Pour in the blended tofu mixture, then add finishing ingredients. Taste and adjust according to your preferences.
Spoon the mixture into the silicon loaf pan. Use wet hands to smooth the top down as best you can.
Place the silicon pan on an oven tray so it sits evenly, then place into the oven for 30 minutes. Check on the loaf after 30 minutes and turn the oven down to 180C/356F if it’s looking nicely browned on top. Continue to cook for another 30 minutes.
Remove from the oven and allow to cool for 20-30 minutes at least. This loaf needs time to set up to make is easy to slice, so I recommend making it ahead of time.
When you’re ready to serve, simply reheat and slice.