In a large bowl or container place meat, then add puree, sugar, soy sauce, sliced scallions, ground black pepper, sesame oil and a handful of julienned carrots (optional). Mix everything together so marinade could code each slice of beef; cover with plastic wrap and place in the fridge for an hour or more. You can use less soy sauce and add salt to taste, instead.
Preheat the grill or lightly oiled/greased saute pan or skillet and add beef slices. Cook until meat is no longer pink and it starts to sizzle and juices are almost gone.
You can place beef to marinade in the fridge overnight. I like to do it at least an hour in advance, but the more is marinating, meat becomes more tender. I have done overnight before! I used Beef Tenderloin today, but The best beef for this is rib-eye steak or top sirloin. Of course, you may use any cut but you will know the difference if you make it with ribeye steak because fat is where a lot of the distinctive flavor of beef comes from, making ribeye one of the richest, beefiest cut available. You may also find it already precut beef in the Korean or Asian market "for bulgogi". If you do not want to use 7 Up or Asian Pear then add 1-2 Tbs. (more) of Sugar. Both 7 up and Asian pear not only make beef tender but also gives sweetness, if you omit you have to add sugar or even honey if you desire.