For the Cashew Cream:
Soak the cashews for 30 minutes to soften. Rinse and drain the cashews and place in a blender.
While the cashews are soaking, place the dried porcinis in a small saucepan with 3/4 cup vegetable broth and heat on medium-low heat to soften for a few minutes.
RESERVE and STRAIN the broth from the porcinis and add it to the blender. Chop the porcinis and set aside.
Add the lemon, apple cider vinegar, and salt to the blender and puree until smooth. You might need to add up to 1/4 cup more vegetable broth to make it smooth. Set aside the cashew cream.
While the cashews are soaking, chop the mushrooms, onion, garlic, and rosemary.
In a large sauté pan over medium heat, sauté the red onion and rosemary until soft, about 2 minutes. Add mushrooms and garlic and sauté for 1 minute.
Add 1 Tbsp. soy sauce or tamari and simmer for about 10 minutes to allow the juices to release and develop the flavor. Deglaze with white wine and cook for about 1 minute until it;s reduced.
Add the cashew cream, 1 more Tbsp. tamari or soy sauce, and 1 and a 1/2 cup of vegetable broth and stir to combine. Season with a dash of white pepper. Season with more salt if needed.
Let simmer for up to one minute until the sauce comes together.