Slice livermush into 6 ½ inch thick slices (3 per sandwich).
Heat a pan over medium heat until hot. Add oil and add livermush slices. (You may need to fry in batches). Cook until pan side darkens, about 5 minutes. Flip and cook another few minutes.
First Way
Layer fried livermush on the bun. On the top bun, liberally cover with grape jelly.
Second Way
Layer fried livermush on the bun. On the top bun, liberally cover with mustard. Add chopped onion and top with bun.