Warm the grape seed oil in a large pot over medium to high heat. Add in the onions, ginger, cumin, cardamom and sweat for one minute without browning. Then add in half the diced apples, sultanas, white wine vinegar, sugar and mint. Simmer for 30 minutes until the apples cook down. Then add in the remaining apples and cook for another 5 minutes. Remove from the heat and chill.