Heat oven to 200°C.
If making the tahini yoghurt, combine all ingredients and place in the fridge until needed.
Keeping the skin on, cut potatoes into small bite-sized chunks, around 1.5 – 2cm.
Place 2 tablespoons of butter into a medium-sized oven roasting tray and heat in the oven for 1 minute until the butter has melted.
Place potatoes into the melted butter tray and toss to coat well. Season with salt. Roast for 20 minutes.
Remove the tray from the oven and pour over the umami bomb sauce. Coat the potatoes evenly then return to the oven for another 25 minutes, occasionally tossing the potatoes around to ensure even cooking. After 25 minutes the potatoes should be deliciously caramelised, fluffy and crisp.
Once out of the oven, give the potatoes one final toss to completely cover in the miso butter. Taste and season with salt if needed.
Transfer potatoes to a serving plate. Sprinkle with sesame seeds and spring onion. Serve with tahini yoghurt and chilli sauce.