Remove the base of the chicory, then thinly slice it. Finely chop the spring onions and chilli.
Heat 1 Tbsp olive oil and gently sauté the chopped vegetables and the capers (under over, over low heat) for about 5-6 minutes.
When the chicory is tender, put the fish on top, then squeeze over the lemon juice and scatter the lemon zest over everything. Season with salt and pepper, then put on the lid, turn up the heat a bit and let the fish steam for about 5-8 minutes (depending on the thickness of the fillet).
When the fish is cooked through, serve with the chopped herbs scattered on top.