In a mixing bowl, whisk together vegetable oil, sesame oil, soy sauce, brown sugar, minced garlic, grated ginger, and black pepper. Add flank steak, ensuring it is well coated, and refrigerate for at least 30 minutes or overnight.

Cook jasmine rice according to package instructions. While the rice cooks, chop green onions, shred carrots, and slice cucumber. Set aside.

In a small bowl, combine mayonnaise or Greek yogurt, sriracha sauce, lime juice, and honey. Whisk until smooth and adjust sriracha according to spice preference.

Heat a heavy skillet over high heat, adding vegetable oil once hot. Sear marinated steak for 3-5 minutes per side until dark crust forms. Let it rest for 5-10 minutes.

Assemble bowls by dividing rice, layering steak, and adding green onions, carrots, and cucumber. Drizzle with spicy cream sauce and garnish as desired.