Preheat oven to 200°C.
Line a large roasting pan with baking paper. In a bowl mix miso, garlic, ginger, brown sugar and the oils together.
Add the Inca Gold potatoes and mushrooms and coat in the mixture. Season with salt and pepper.
Pour the mixture into the prepared pan in a single layer and roast for 30 minutes, turning after 15 minutes.
Transfer to a serving dish. Garnish with spring onions and sesame seeds.
To serve: Serve with pan-fried fish and salad for a quick and tasty meal.