Heat a large pot over medium heat and add the olive oil.
Once the oil is hot add the onion, garlic, celery and carrots and saute until the onion is soft and transluscent.
Add the salt, pepper, thyme, and paprika and stir well.
Deglaze the pot with the red wine (use a splash of vegetable stock in place of the red wine if you'd prefer), and scrape up all the brown bits off the bottom of the pan from cooking the veggies.
Add the Worcestershire sauce (if using), tomato paste, and the mushrooms, and stir well. Cook for a few minutes until the mushrooms just begin to soften.
Add the stock, potatoes, and lentils. Stir very well and cover the pot.
Let the stew cook, covered, for about 30 minutes. Turn the heat down to medium-low and stir regularly to prevent the stew from burning on the bottom of the pot.
Test the potatoes with a fork. If they're soft, add the frozen green beans and stir well. Cover and let the green beans soften in the hot stew for 4-5 minutes.
Serve with fresh bread.