Mackerel is a delicious and a sustainable fish and very reasonably priced but not as popular as it should be.
For the years I ran the restaurant I tried to persuade people to eat it by putting it in the menu but it was decidedly a non-runner.
This I firmly believe is that it is a bony fish and people are afraid of the bones. There are various ways to get rid of the bones, my wife has an ingenious method of pressing on its back to remove them, but I have found the only fool proof way to get rid of all the bones is to cut them out, not at all difficult with a sharp knife.
Buy the mackerel filleted by the fishmonger, this gets rid of some, but by no means all, of the bones.
Now if you lay a fillet on a board you will see that the principal bones run in a straight line down the middle.
Using your sharp knife cut at each side of the line of bones effectively removing a narrow band of flesh with the bones in.
Throw this away, or use with the head to make a fish stock.
Now check the edges of the fish with your fingertips and cut out or pull out any remaining bones there. Do this thoroughly as mackerel bones are very unpopular.
This divides each fillet into two boneless goujons, each fish into four.
Now you can cook the fish in different ways.

Baked Goujons of Mackerel
(for 4)

4 Large Filleted Mackerel
Juice of 1 Lemon
4 Tablespoons of Olive Oil
Salt and Pepper
4 oz. (110g) Fine Breadcrumbs

Caper Mayonnaise:
6 tablespoons mayonnaise (Home made if possible)
4 teaspoons roughly chopped Capers
Mix these together to make the sauce, you may add some of the vinegar from the capers to sharpen the sauce.

Put two tablespoons of the oil on a baking tray and turn the goujons on this, coating them with oil and laying them together skin side down.
Pour the lemon juice over these and sprinkle over some salt and a liberal grinding of black pepper.
Cover these with a layer of the breadcrumbs and then sprinkle over the remaining oil.
Pre-heat the oven to 200C, 400F, Gas 6 and cook the goujons until opaque all through, this should take about five minutes.
Serve these immediately with the caper mayonnaise.

Goujons of Mackerel with Garlic Mayonnaise

(for 4)

4 Filleted Mackerel
1 Beaten egg
175g (6 oz.) Fresh Breadcrumbs

2 Egg yolks
2 crushed or finely chopped cloves Garlic
300 ml (10 oz.) Olive Oil (not extra virgin)
Salt Pepper and a teaspoon of vinegar.

Garlic Mayonnaise

Mix the garlic with the egg yolks and dribble in the oil beating all the time to make the sauce.
Season this with salt and pepper and a teaspoon of vinegar.

Make the goujons as described above.

Dip these in egg and then in the breadcrumbs.
(If you have some fresh herbs in the garden mix some chopped herbs with the crumbs)
Fry these in batches in olive oil until brown on all sides and cooked through.

Serve with the sauce on the side.