Place the eggs in a large pot and cover 1-2 inches with cold water. Cover. Bring water to a boil and boil for 8 minutes. Turn off the heat and let stand, covered, for 5 minutes and then drain the water.
Cool the eggs under cold running water and peel, discarding the shells.
Roughly mash the eggs in a bowl with the mayonnaise, mustard, and pickle relish. Season with salt and pepper.
To serve, half the tomatoes and clean out the middle or use whole grain bread. Garnish with sliced green onions, if desired.