In a large saucepan, heat oil and butter over medium-low heat.
Add the onion and garlic and sauté until the onion is golden brown, about 15 minutes.
Add the fresh and reconstituted mushrooms and cook, uncovered, until tender, about 30 minutes.
Add the stock, chiles, and bay leaf and simmer, covered, for 20 minutes.
Add the beans and continue to simmer until heated through, about 10 more minutes.
Season to taste with salt and pepper.
