Mix the onions, feta, garlic, oil and salt in a bowl, spread on a baking tray lined with baking paper.
Approx. 15 mins. in the centre of an oven preheated to 220°C. Remove from the oven, set aside approx. ⅓ of the spring onions and the roasted feta.
Squeeze the garlic cloves out of their skins, puree until smooth along with the remainder of the spring onions, the feta and all the other ingredients. Serve the dip with the reserved spring onions and the feta.