Combine the lemongrass, soy sauce, fish sauce, lime juice, vegetable oil, ginger, garlic, sugar, and sesame oil together in large baking dish.
Coat each side of the ribs in the marinade then nestle into the baking dish.
Cover with plastic wrap and refrigerate for 6 hours, flipping them occasionally.
Remove the ribs from the refrigerator 30 minutes prior to cooking.
Heat the grill pan over medium-high heat; coat the pan with cooking spray then, working in batches, sear the ribs until browned, 4-5 minutes per side for medium-rare.
Transfer to a plate and let rest for 5 minutes. Top with sliced green onion and fresh cilantro leaves. Serve and enjoy.