1. In a flameproof dish, heat the oil on medium. Sauté the onion and garlic for about 4-5 minutes. Transfer to bowl and allow to cool.
2. Add the mince, mint, chilli and cumin to the onion mixture. Season and mix well.
3. Roll into 12 balls, filling each with a feta cube. Place on a tray and chill for about 30 minutes.