Heat oil in a large pot over medium heat.
Add onion, carrot, and celery along with a couple pinches of salt and pepper.
Cook, stirring occasionally for 8 minutes.
Add mushrooms, garlic, thyme, oregano, sage, and a couple pinches of salt and pepper.
Cook, stirring frequently, for 3-4 minutes.
Add flour and stir to evenly coat everything. Cook, stirring frequently for 1 minute.
Stir in balsamic vinegar and soy sauce to deglaze the pan, scraping the yummy bits off the bottom.
Add potatoes, lentils, tomato sauce, broth, and bay leaves, along with a couple pinches of salt and pepper.
Bring to a simmer over medium-high heat, stirring occasionally so that the lentils don't stick to the pan.
Turn heat to low and simmer gently for 10-15 minutes or until the potatoes are fork-tender. Season to taste with salt and pepper.
Garnish with fresh parsley, serve with mashed potatoes, and enjoy!
