Heat the butter and oil in a heavy-based ovenproof saucepan over a medium heat, then add the whole new potatoes. Cover and cook for 15 mins, shaking the pan every few minutes to ensure the potatoes cook evenly. When ready, the potatoes should have just started to soften and will be well-browned.

Heat the oven to 200C/180C fan/gas 6. Scatter the lemon zest and herbs over the potatoes, season, cover again and shake to combine. Transfer to the oven and bake for 15-20 mins until cooked through and tender.