Start by making the miso-orange glaze. Add everything into a saucepan and cook on high heat until a boil. Reduce the heat to a simmer and let the sauce reduce down and thicken into a syrup like consistency, about 5 minutes.
In the meantime, prepare the dipping sauce by simply blending all the ingredients into a food processor/blender until creamy.
Now slightly brush each mushroom with the olive oil, and a sprinkling of salt and pepper. Using a grill pan, grill the mushrooms on high heat until golden brown, about 1 minute each side.
While on the grill, generously brush the top side of the mushroom with the miso-orange glaze. Once brushed with the glaze, flip and cook the glazed side for 1-2 more minutes, or until tender. Repeat this step for the remaining side. Serve the grilled mushroom with the tahini dipping sauce and enjoy!