Discard the husks and silk from the corn. Stand each one upright in a shallow bowl or plate, and cut off the kernels with a sharp knife; put to one side.
Halve the tomatoes, and squeeze out the seeds. Chop or dice the tomato flesh. When tomatoes are going to be cooked only briefly, as in this recipe, the skins do not need to be removed; they will not have time to become detached, and roll up into tight, disagreeable little spikes.
Lightly season the tomatoes and the salmon fillets, and put these to one side. Peel, cut up and boil the potatoes until tender, and then drain and mash them with whatever additions you choose, keeping them warm.
Put the corn and tomato in a saucepan with a nut of unsalted butter or a little extra-virgin olive oil, and some shredded basil. Allow this to simmer on the gentlest possible heat, while you cook the salmon.
Have a non-stick or well-seasoned pan very hot, and in it put the salmon, flesh side down, for 30 seconds or so. Turn the fish over, and let it cook on the skin side until done to your liking.
Spoon the vegetables onto heated plates, the mashed potatoes on top, and then place the piece of salmon on top of each heap. Extra basil can be used for garnish.