How to make
Clean the mackerel of scales, guts and black flakes. Remove the head, wash the mackerel and cut it into thick about 1/2″ (1.5 cm) slices.
Boil in some water for about 10 mins. In a separate pot, put oil and the chopped onions - first the halves, then each half cut into strips. Add a little water and saute lightly.
Then add the pieces of fish, a little salt, pepper and boil until the onions soften. Finally, add the tomato puree and boil the fish some more.