Remove the skin and seeds from the pumpkin and slice it thinly.
Cut the ciabatta bread in half.
Season the beef for bulgogi with soy sauce, sugar, minced garlic, and pepper.
Add oil to a pan and grill the pumpkin slices until golden brown.
In the same pan, stir-fry the seasoned beef.
Layer the grilled pumpkin and bulgogi beef on the ciabatta in order.
Add salad greens if desired, and complete your sandwich.