Oil your grids and preheat your grill to 400 to 450°F.
Season the salmon lightly with salt and pepper, any other herbs you like too, but nothing sweet. Grill the salmon over direct heat for 10 to 15 minutes, until it flakes easily.
Allow the salmon to cool when it is done. If you're serving it right away, spread the slices of bread with butter, and toast them like you would grilled cheese.
Remove the skin and combine the salmon with the mayonnaise. I didn't give an exact measurement because this is something personal to everyone. Just make sure that the salmon will stay together with the amount of mayo you use.
Place your toppings on the bread, followed by the salmon and serve. Or store the prepared salmon for use for up to 24 hours.