In a large heavy bottomed pot over medium-high heat, heat 2 tablespoon oil. Add mushrooms and sear until deeply brown, remove from skillet. Lower heat to medium and add remaining oil. Add onion, celery, parsnips, and butternut squash, cook until starting to become well browned, about 12 minutes.
Stir in tomato paste and garlic and cook, stirring often, about 2 minutes. Stir in miso paste, immediately deglaze with wine, and cook 1 minute more. Add the mushrooms back in and stir in the lentils. Sprinkle everything with flour and stir until well incorporated.
Cook 1 more minute and then add vegetable stock. Season with salt and pepper. Bring to a simmer and cook until the lentils are al dente, about 15 minutes.