Add everything to a food processor fitted with the blade attachment. Cover and mix on high speed until very smooth and well blended.
¾ cup Greek-style yogurt, 2 cups soft mixed herbs, 2 green onions or ¼ cup chopped chives, 2 cloves garlic, 2 tablespoons lemon juice, ½ teaspoon lemon zest, ⅓ cup extra-virgin olive oil*, 2 teaspoons capers, ½ teaspoon sea salt*, Freshly ground black pepper*, Pinch of chilli flakes