Hearty liverwurst on rye bread with mustard and onion is a protein-packed, old-world deli sandwich. This savory classic delivers rich, earthy flavors for adventurous eaters.
Spread the butter thinly on one side of each rye bread slice for flavor and moisture control.
Thinly slice the yellow onion, ensuring even rings to layer onto the sandwich.
Evenly spread yellow mustard onto the unbuttered side of two bread slices, reaching all corners.
Arrange 3 oz of liverwurst on each mustard-slathered slice, spreading it gently to avoid tearing the bread.
Top with onion slices, a sprinkle of black pepper, and the remaining bread slices, buttered side out; slice in half and serve immediately to preserve texture.