Melt the butter and let it cool down. Wash the potatoes well and cut them in half lengthwise. Mix in a large bowl with butter, oil, sesame, pimento and sea salt.
Spread the potatoes on the fat pan of the oven. Roast in the preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer) for 45-50 minutes. After approx. 30 minutes, turn once if necessary.