To prepare the broth:

• In a large pot, heat the olive oil over medium heat. Add the onion, celery, carrots, garlic, bay leaves, thyme, and black peppercorns. Sweat the vegetables, stirring occasionally, until they soften and become fragrant, about 5-7 minutes.
• Pour in the white wine and let it reduce until nearly dry, about 10-15 minutes.
• Add the mushrooms and water, then bring the mixture to a boil.
• Reduce the heat to low and let the stock simmer gently for 1-2 hours, allowing the flavors to develop.
• Strain the stock through a fine-mesh sieve, pressing on the solids to extract as much liquid as possible. Discard the solids.
• The final yield should be approximately 2 quarts of mushroom stock.