Place steak in freezer for 1 hour until firm, but not frozen. Cut steak, against the grain, into 1/8-inch-thick slices. Combine steak and 1/2 cup San-J Korean BBQ Sauce in medium bowl. Cover with plastic wrap and let marinated for 30 minutes.
Preheat oven to 450°F and line 2 rimmed baking sheets with parchment paper. Heat oil in large wok or skillet over medium-high heat until it just begins to smoke. Add steak and cook, stirring constantly until steak is golden-brown and sauce reduces, about 4-5 minutes. Remove from heat and set aside.
Place 1 crust on each prepared baking sheet. Spread 1/4 cup San-J Korean BBQ Sauce over each crust. Top evenly with mozzerella, steak mixture, kimchi and red onions.
Working in batches, bake until crust is light golden-brown and cheese is melted, about 10-14 minutes. Repeat with remaining crust. Drizzle with remaining San-J Korean BBQ Sauce and garnish with green onions. Slice and serve.
* The Gluten Free recipes that appear in this website incorporate a variety of San-J's products that are Certified Gluten Free. Please be sure to consider the other ingredients to make sure they comply with your dietary needs and restrictions.