Drain the salmon. Remove skin and bones, if desired and break into large chunks
Heat 4 - 5 drops of olive oil a frying pan, then add a tortilla turning it around in the pan to spread the oil evenly. Top with half the grated cheese and allow it to melt for a moment
Sprinkle one half of the tortilla with half the salmon flakes, half the avocado and half the chopped tomato. Cook for another few seconds, then fold over and slide from the pan onto a plate
Cook the remaining tortilla in the same way. Cut in half and serve at once.