Vegan Lentil Loaf

0 Cook the Lentils: Add the brown lentils, red lentils, vegetable broth, and water to a large pot. Bring to a boil over high heat; reduce the heat to low, cover, and let simmer for 30 minutes. 
1 Prep: Preheat the oven to 375F once 10-15 minutes have passed. Line a 4x8” loaf pan with parchment paper and set aside.
2 Aromatics: Warm the oil in a large sauté pan over medium heat. Add the onion, celery, and carrot and sauté for 5 minutes, stirring occasionally. 
3 Seasonings: Add the mushrooms, rosemary, thyme, sage, and 1 tablespoon tamari. Sauté for 8 to 10 minutes, until almost all of the liquid has evaporated from the pan. Add the garlic and sauté for an additional 1 to 2 minutes. You want the vegetables to be as dry as possible!
4 Strain the Lentils: Once the lentils have finished cooking, transfer them to a fine METAL strainer (do not use a strainer with large holes) and use a spatula to “stir” the lentils and remove as much extra liquid as possible. The Red Lentils will break down and become a thick puree, while the Brown Lentils will remain relatively intact.
5 Combine: Transfer the lentils and cooked vegetable mixture to a large bowl. Add in the walnuts, ground flax, and remaining tablespoon of tamari. Mix until everything is evenly incorporated, then use a spatula to firmly pack the “batter” into the loaf pan. There should be a little extra batter protruding from the top of the pan – I like to round this out to create an even top of the loaf.
6 Bake: Bake the loaf in the oven for 50 minutes, then remove and let sit in the pan for 5 minutes before carefully transferring to a cooling rack. Let sit for at least 30 minutes before serving. You can also let the lentil loaf sit in the fridge overnight if you’d like it to be firmer.
7 Serve: serve warm, topped with gravy or as desired. Leftovers can be reheated in the oven or toaster oven at 300F for 20-25 minutes. Store leftovers in the fridge for up to 5 days, or pre-slice and freeze for up to 2 months.