Canned Mackerel Toasties Open one can of mackerel , drain the water and put it in to a bowl. Slice an onion finely, about 1/2 tsp pepper, Slice some chillies, ( this step is optional), enough salt and lime or lemon. Prepare them. Melt butter in a mixing bowl. This is about 50g. More the butter more tastier it is. Crush the fish using a fork. Add the melted butter in it and mix well. Now squeeze the lemon in to it. Add onion and chillies, salt and pepper. Mix well.. Lay two slices of bread on a chopping board. Spread the prepared mix. Close the bread and press. Toast it in a grill or in a sandwich press. Enjoy. Simple meal.