As I mentioned, I am using store cupboard ingredients here, that’s why the amount of potato looks so odd. The drained weight is 345 grams apparently.  The canned potatoes are already cooked too, so all you have to do is warm them through.  With the mackerel, if it’s in oil in the can then you can just pour this oil into your pan to start frying the onions and garlic and you don’t even need the extra tablespoon.  This imparts a lovely, fishy smell right from the start too, which is nice.   I am sure you could use all fresh ingredients if you wanted to, but for me, this dish is all about ease and speed, and it still tastes great.

Open the can of mackerel fillets and pour the oil into the saucepan to start frying the chopped onion.   If the mackerel is in brine or something, then you will need to drain this off and you will need that tablespoon of veg oil.  Anyway, fry the onion until soft and add the garlic and fry that for a minute.  Stir in the flour next, this will make everything clag up together into a thick paste, don’t worry about that, it’s supposed to happen.  At least I think it is!  Add some of the milk and water and stir it in until the paste loosens up, add the rest of the milk and water and stir briskly with a whisk or fork to get rid of any lumps you may have missed.  You will now have a rather pallid, thin, soupy thing looking back at you, again, don’t worry, it gets better.

Season with salt and pepper, add the frozen spinach, the drained can of sweetcorn, the drained can of potatoes and the frozen prawns if you’re using them.  Break up the mackerel fillets into bite-sized pieces as you add those and bring the whole thing to the boil.  Reduce the heat to a simmer and leave it for 10 to 15 minutes or until the potatoes are soft and the sauce has become thick and creamy.