Put a large pan of cold water on the heat. We are going to use this to make the hollandaise and then poach the eggs.
Make the reduction by adding the white vinegar, black peppercorns and bay leaf to a small pan. Reduce by half.
Discard the peppercorns and bay leaf then add to a round metal or Perspex bowl whisk in the eggs yolks( make sure the reduction is ant boiling, you don’t want to cook scramble the egg yolks)
Take your melted butter and remove the impurities on top, the milk part of the butter will be underneath with the fat on top. ( when melting the butter leave this in a warm place or your lowest heat setting. Do not boil!)
Put the bowl on the steaming water pan and you just want it hot enough to cook the eggs until they treble in volume, make sure you season at this stage. You can use a tea towel to lift up the bowland you should be able to hold your hand flat underneath without it burning. That is the right temperature for cooking the eggs. Be careful not to scramble them.
Remove the bowl and dampen a tea towel to use as a firm stable base, just twist it first and make a circle and place your bowl in the middle this will make it stable as you will need to hold the whisk in one hand and add the butter with the other.
So with your bowl firmly on the worktop start whisking and adding the butter very gradually being careful not to over add and mix this will split the mixture and you’ll have to start again. If this happens you’ll see and curdled separated mess. Don’t worry just save the liquid in one container wash you bowl and whisk a single yolk in the bowl and start adding the split liquid back in the new yolk.
Little by little add the mixture and if a little thick and a tad of hot water or the milky base of your butter.
Set aside and grill you mackerel fillets lightly.
Put spinach into hot pan to wilt then season. Set aside.
Turn up the temperature of the water to 90-95 degrees ready for poaching eggs
Crack the eggs into individual cups to make it easy to pour in your eggs the water.
Create a min vortex by twirling a spoon inside clockwise then add your eggs.
Leave for three minutes or until texture like jelly and then they are ready.
Cut muffins in half and toast then add spinach grilled mackerel fillets, poached eggs and top with sumptuous hollandaise sauce
Garnish with parsley leaves, salt and pepper.