In a high-speed blender, combine raw cashews, 1/2 cup water, miso paste, and 2 large mushrooms cut into quarters. Blend until creamy. Set aside.

Thinly slice the remaining mushrooms.

Heat olive oil in a soup pot over medium heat. Sauté chopped onion and minced garlic for a few minutes until fragrant.

Add sliced mushrooms and a pinch of salt. Cook, stirring, until mushrooms soften and release their liquid.

Add 3 1/2 cups water, lentils, brown rice, vegetable bouillon cube, dried rosemary, dried thyme, and a pinch more salt. Bring to a simmer, then cover and cook for 30 minutes.

Check rice and lentils for doneness; cook 5 more minutes if needed. Stir in the cashew cream and cook for another 5 minutes.

Season with freshly ground pepper and additional salt to taste.