Sauté the Soffritto: Heat the olive oil in a large skillet or Dutch oven over medium heat. Add the finely chopped onion, carrot, and celery. Cook for 3-5 minutes, stirring occasionally, until the onion turns translucent and softens.
Brown the Mushrooms: Add the finely chopped mushrooms to the skillet and continue cooking for about 5 minutes, until the mushrooms have released most of their moisture and are starting to brown.
Build the Base: Stir in the soy sauce, minced garlic, and dry lentils. Cook for 1 minute more, stirring frequently, until fragrant.
Deglaze: Pour in the red wine, scraping up any browned bits from the bottom of the skillet. Let it bubble for about a minute until most of the liquid has evaporated.
Simmer the Sauce: Add the diced tomatoes, vegetable broth, tomato paste, bay leaf, thyme, smoked paprika, miso paste (if using), and salt. Stir everything together to combine and bring the mixture to a boil.
Cover and Cook: Reduce the heat to low to maintain a gentle simmer. Cover the skillet and cook for 30 to 35 minutes, or until the lentils are tender and cooked through. If the sauce becomes too thick during cooking, stir in a splash of vegetable broth or water to loosen it.
Finish the Ragu: Remove and discard the bay leaf. Taste and adjust seasonings as needed. Stir in the crushed walnuts, if using, for added texture.
Serve: Spoon the rich mushroom and lentil ragu generously over your cooked pasta of choice. Garnish with sautéed garlic mushrooms, a sprinkle of vegan parmesan, and fresh herbs. Enjoy immediately.