Bulgogi is a Korean classic of marinated beef. It is one of the most popular foods among all Koreans. It is one of the country's most successful culinary exports.
The meat is seasoned with sesame and scallion, and has ripe pears in the marinade to tenderize the meat and add a characteristic sweetness. Round, pale yellow Asian pears are traditional, but normal pears are just fine.
Perilla is a common Korean herb. But if you cannot find it, you can try other herbs like shiso or cilantro.
This are pictures of beef bulgogi: