Slice each cucumber in half lengthwise.
Using a spoon, scoop out the seeds to create a shallow channel down the center.
Cut each half into 2 or 3 pieces.
Heat a skillet over medium-high heat.
Cook the beef bulgogi until browned and caramelized.
Let cool slightly, then roughly chop into bite-sized pieces.
In a small bowl, combine the chopped kimchee and Kewpie mayonnaise.
Spoon about 1 tablespoon or more of kimchee mixture into each cucumber boat.
Top with a generous portion of beef bulgogi.
Garnish with sliced green onions and serve immediately.