In a saucepot, cover dried mushrooms with stock and add in a bay leaf. Bring to a boil and reduce heat to a simmer. Keep at a low boil to reduce liquid by a third and soften mushrooms, about 20 minutes. Remove mushrooms with slotted spoon and chop.
Heat olive oil, 2 turns of the pan, in a Dutch oven over medium-high heat. Add 2 tablespoons butter and melt it into hot oil. Add fresh sliced mushrooms to the pot and brown, 15-20 minutes. Add shallots, carrot, garlic, herbs, salt and pepper, and stir a few minutes to soften veggies. Stir tomato paste into vegetables and cook 1 minute then sprinkle in flour and combine well. Whisk in wine and cook to reduce by half. Add porcini-flavored stock and stir in porcinis. Simmer the stew until ready to serve.