In a mixing bowl, whisk together vegetable oil, sesame oil, soy sauce, brown sugar, minced garlic, grated ginger, and black pepper until well combined. Add the flank steak, ensuring it is fully coated in the marinade. Cover the bowl with plastic wrap and refrigerate for at least 30 minutes (up to 2 hours).

While the steak marinates, whisk together mayonnaise, sriracha sauce, lime juice, honey, and a pinch of salt in a small bowl. Set aside in the fridge.

Preheat a grill pan over medium-high heat for about 5 minutes. Grill the marinated steak for 4-5 minutes on each side until an internal temperature of 130°F is reached for medium-rare. Let the steak rest for at least 5 minutes before slicing it against the grain.

Prepare your bowls by placing cooked jasmine rice at the bottom, layering sliced steak on top, followed by green onions, shredded carrots, and cucumber.

Drizzle the spicy cream sauce over each bowl and sprinkle with optional toasted sesame seeds. Serve immediately.