In a medium bowl, whisk together soy sauce, sesame oil, brown sugar, minced garlic, and grated ginger. Add the flank steak, ensuring it's evenly coated in the marinade. Cover and refrigerate for at least 30 minutes.

Prepare jasmine rice according to package instructions. Rinse rice, combine with water in a saucepan, and bring to a boil. Reduce to simmer, cover, and cook for about 15 minutes until fluffy. Fluff the cooked rice and set aside.

In a separate bowl, whisk together sour cream, Sriracha sauce, lime juice, honey, salt, and pepper until smooth. Adjust the sauce for preferred spice level.

Heat a grill pan over high heat. Remove the flank steak from the marinade and grill for 5-6 minutes per side, until medium-rare (about 135°F).

Transfer the steak to a cutting board and let it rest for 5 minutes. Slice against the grain into thin strips.

In the same grill pan, heat vegetable oil over medium-high. Add mixed vegetables and sauté for 5-7 minutes until vibrant, tender, and slightly charred.

In serving bowls, layer jasmine rice, sliced steak, and sautéed vegetables. Drizzle with spicy cream sauce.

Sprinkle with sesame seeds and chopped green onions for garnish. Serve immediately.