Heat the olive oil in a large pan or heavy lidded pot over medium heat. Once hot, add the mushrooms. Cook for 6-8 minutes, stirring infrequently, until the mushrooms are browned and any water has evaporated.
1 tablespoon olive oil, 200 grams mushrooms
Stir in the onion and cook for another 8-10 minutes, stirring occasionally, until translucent and fragrant. It may brown slightly and that's fine, but reduce the heat if needed.
1 large onion
Add the grated vegetables and garlic and cook for another five minutes, stirring occasionally. The vegetables will stick a bit to the bottom of the pan, but will be lifted by the wine and broth later.
1 medium carrot, 1 medium parsnip, 2 cloves garlic
Stir in the lentils, spices, and herbs. Add the wine and stir well to release any bits that might be stuck.
100 grams dry red lentils, 1 teaspoon smoked paprika, 1 teaspoon sea salt, ½ teaspoon black pepper, ½ teaspoon hot pepper flakes, ½ teaspoon dried thyme, ½ teaspoon dried rosemary, 50 ml dry red wine
Pour in the vegetable broth and be sure to scrape down the sides of the pot if anything has made its way up. Bring to a boil, then reduce the heat and simmer, covered, for 15 minutes.
300 ml vegetable broth
Once the lentil mixture has cooked - note that the lentils won't be cooked through - taste and adjust seasoning (don't eat a lentil). Set this mixture aside to cool until room temperature or just warm. This will go faster if you transfer it to a large bowl or set in an unheated area. This is a good time to toast the nuts.
Once cooled, preheat the oven to 180°C (350°F) and line a 1.5 litre*** (2 lb.) loaf tin with parchment paper. stir in the nuts, oats, and chickpea flour. Mix in the eggs until very well combined. The mixture will look a little loose, that's normal.
Transfer the nut roast mixture to the loaf tin and gently press the top with a spoon or spatula, making sure it's evenly spread out. You want to compress it as much as possible.
Bake for 30 minutes, covered (I use a sheet of parchment paper). Remove the covering and bake for another 20 minutes to brown the top.
Turn out onto a serving tray or cutting board and cool for 10 minutes before slicing and serving.
Notes
Use 200 grams combined of root vegetables if you have one large and one small, for example.* To omit the wine, substitute 1 tablespoon of balsamic vinegar and an extra 3 tablespoons of vegetable broth.** To toast the nuts, start with raw unsalted nuts. Add them to a dry frying pan and cook over medium heat, stirring constantly, until fragrant, shiny, and starting to brown slightly. They must be watched as they burn quickly.*** This is a standard loaf tin. If yours is slightly larger, that's fine, but the mixture will fill it to the top so I don't recommend trying to use a smaller container.