To make the salsa, gently sauté the onions in the butter and the oil until soft but not quite golden.
Add the wine and simmer until reduced by half.
Stir in the remainder of the ingredients and simmer for 3 minutes.
Cut your potatoes so they are all roughly the same size and cook in boiling salty water until softened.
Meanwhile, heat the oil in a frying pan until hot and then fry the salmon, skin down for 3 minutes or so until the skin is nice and crispy.
Flip the salmon over onto the other side for 30 seconds to 1 minute (depending on the size) and add the nob of butter, making sure the salmon is well coated.
Plate all your salad and potatoes, lay the salmon on top and then drizzle with the shrimps and the juice.