During the first couple of weeks the persistent Breton drizzle rarely abated, the rolling clouds swept from deep coal to lighter greys, with barely a glint of blue. We went on foggy walks through swampy fields, tore out weeds under the rain, wore thick sweaters, spent evenings by the fireplace. There wasn’t much outdoor cooking.
And when it is too wet to grill mackerel on an open fire, the next best thing is to slather the fish with mustard on both sides and bake it in the oven. This is how we always prepared mackerel in the family. Short of outdoor grilling, it is the best.
Fish is pretty easy going and doesn’t need much in terms of preparation; the tricky and single most important thing is the cooking time. It is very easy to overcook and that ruins everything. This is particularly acute with mackerel: well cooked it is succulent, overdone it becomes heartlessly dry.
I usually count one mackerel per person, but here we’ve found very small line-caught mackerel that were barely enough for one, and occasionally I’ve seen mackerel large enough to be shared. When I’m not sure I seek advice from the fishmonger.
One medium mackerel per person, whole but gutted
Freshly ground black pepper
Hot Dijon mustard
Preheat the oven to 375°F (190°C).
Season the gutted belly cavity of the mackerel with a pinch of salt and freshly ground pepper; stuff with a sprig of thyme.
Drizzle a little olive oil onto a baking dish large enough to hold all the mackerel.
Slather a thin layer of mustard on both sides of each fish, place into the baking dish and slide into the oven.
Bake for 10 to 12 minutes; this depends on the size of the fish, naturally, and larger ones could take a few minutes longer. **As it is absolutely essential not to overcook fish, rather risk having to pop it back into the oven for a minute if it is still raw inside (the flesh would still be slightly translucent).**
Serve immediately, preferably with mashed potatoes.