Preheat the barbecue. Trim the base of the cauliflowers so that they sit flat, then cut into 2 cm-thick slices.
In a small bowl, mix together 3 tbsp of the oil with the caraway seeds and garlic.
Season, then brush the oil all over the cauliflower steaks.
Cook for 5-6 minutes each side until tender.
Meanwhile, mix together the chopped herbs, spring onions, chilli and remaining 3 tbsp of oil in a small bowl. Squeeze in the juice of ½ a lemon and taste – add a little more lemon juice or oil to taste.