Mix half the butter with the mustard.
Wash, dry, and thickly slice the tomatoes.
Peel and grate the onions.
Remove the fat from the ham and cut the ham in strips.
Wash and shake the chives dry and chop.
Heat the remaining butter, whisk the eggs with the salt and pepper, mix with the strips of ham and heat the eggs in the hot butter, stirring constantly, until they thicken.
Spread the bread with the mustard butter and cover with lettuce and tomato slices.
Salt the tomatoes; spread with grated onion.
Top with the eggs and sprinkle heavily with chives.