In a large heavy pot or dutch oven, heat 6 tablespoons of olive oil over medium heat. Add the sliced leeks and cook until softened, about 5 minutes.
Add the onions, carrots and celery to the pot, along with the garlic, thyme, rosemary and bay leaves. Cook, stirring occasionally, until the leeks start to brown.
Add the mushrooms and turnips or rutabaga. Pour in the wine and Worcestershire sauce and reduce the heat to low. Stir in the potatoes and cover the pot.
Make the roux: In a measuring cup, heat the broth in the microwave until it's hot. Heat 3 tablespoons of olive oil in a medium saucepan over medium heat. Whisk in the flour and cook, whisking constantly, until the roux starts to darken, about 4-5 minutes. Gradually add the hot broth while whisking. Add the vinegar, molasses paprika and a dash of tabasco and whisk until smooth. Stir the roux into the stew.
Simmer the stew, uncovered, until all the vegetables are tender, about 1 hour. If you feel the liquid is evaporating too quickly, you can cover it for a while. Season to taste with salt and pepper. Serve with mashed potatoes or crusty bread and sprinkle with parsley.