Preheat the grill to get it really hot.
Smear the mackerel fillets with the Dijon mustard on the non-skin side and grill skin side up until really crispy.
Meanwhile, boil or steam the Tenderstem for about 3 minutes until tender.
In a frying pan fry the breadcrumbs in the olive oil until golden. Turn off the heat and add the zest of 1 lemon and a large handful of freshly chopped basil. Season well with sea salt and black pepper.
Arrange the Tenderstem on warm plates with the mackerel and sprinkle the toasted crumbs over the top. Serve with lemon wedges.
Recipe courtesy of Tenderstem Broccoli