Remove Salmon from the marinade and pat dry keep the marinade for the sauce.
Cut the Bacon in to 5/6 pieces (not to small), then chop the onion, leeks, and tomato flesh into small dice.
Heat your pan with a little olive oil and add the salmon skin side down
add a little butter and cook for 3/4 minutes gently frying.
Turn over Salmon and cook for another 2 minutes
Remove Salmon from the pan, place on a tray/plate, and allow to rest while we cook the garnish and sauce
In the pan add the bacon
Cook until crispy
N.B. DO THIS PART CAREFULLY AS OIL IS HOT - At this stage there will be alot of fat and oil from the bacon, drain most of this off by carefully tilting the pan and pouring the fat in to a heat proof container (once cool dispose of this).
Return pan to the heat with a little of the remaining pan oil and bacon add the onion.
Cook for 3 minute and add the leek - the leek will cook quickly, so keep stirring like you would a stir fry.
add the reserved mariande from the the salmon, allow to cook untillit becomes syrupy, this will happen quickly.
Add chicken stock and simmer; reduce by half to concentrate the flavours and consistency of the stock
When the stock is reduced TURN DOWN THE HEAT TO THE LOWEST SETTING. add the cold butter gently stir to melt the butter when the butter is 50% melted turn off the heat completely,
Continue to stir until the butter and pan juices form a silky smooth sauce.
Roughly chop some parsley
Add the diced tomato to the sauce and stir.
Add the parsley
Return the Salmon to the pan and gently warm through with the heat of the sauce.
Check the seasoning of the sauce may need a pinch of salt, or a few drops of lemon juice.