Saute bacon just until crisp in a large frying pan; drain on paper toweling, then crumble.
Drain off ail drippings, then measure 2 tablespoons and return to pan.
(Set bacon aside for later stage.)
Halve chicken livers; snip out any veiny parts or skin with scissors.
Shake livers with flour and seasoned salt in a paper bag to coat.
Brown slowly in drippings in frying pan; stir in mushrooms and liquid.
Heat, stirring constantly, to boiling; cover.
Simmer 3 minutes, or just until livers lose their pink color.
While livers cook, place tomato slices and bun halves in a single layer on rack in broiler pan.
Broil 3 to 4 minutes, or until tomatoes are heated through and buns are toasted.
Place 2 tomato slices on each bun half; spoon hot liver mixture over, dividing evenly.
Top each with another tomato slice; sprinkle with crumbled bacon.
Garnish with parsley, if you wish.