For a richer flavor, consider using a mix of mushroom varieties, such as shiitake and cremini, in addition to portobello. If you don't have a high-powered blender, soak the cashews in hot water for at least 30 minutes to soften them before blending. Adjust the amount of miso paste to your preference. Start with 2 tablespoons and add more to taste. A splash of dry sherry or white wine can add depth to the sauce during the simmering stage. Garnish with chopped parsley, chives, or a sprinkle of red pepper flakes for an extra touch of flavor and visual appeal.