20²µ/½´Ç³ú dill fronds, plus 2 tbsp chopped dill
30g/1oz fennel fronds
1 lemon, sliced
400g/14oz new potatoes, larger ones cut in half
1 tbsp fresh chopped rosemary
1 tbsp fresh chopped thyme
2 tbsp capers
salt and freshly ground black pepper
2 tbsp olive oil, plus extra for drizzling
1 tbsp salt
4 whole mackerel, gutted