Combine the soy sauce, brown sugar, green onions, sesame oil, grated pear, grated ginger, minced garlic, and sriracha together in a bowl.
Whisk the mixture very well then pour 1/4 cup in a separate container; cover and set aside for serving.
Add the flanken short ribs to the marinade in the ziplock bag and toss to coat evenly.
Refrigerate for 1-24 hours (I marinated for 12 hours).
Remove the meat from the refrigerator 30 minutes prior to cooking.
Heat a grill pan over medium-high heat.
Coat with cooking spray then lay a few of the short ribs in the HOT grill pan and cook for 2-3 minutes then flip and continue to cook for another 2-3 minutes, or until cooked to your desired degree of doneness.
Remove from the pan and set aside on a serving plate with a loose tin foil tent.
Finish cooking the remaining short ribs.
Serve the Korean flanken short ribs sprinkled with toasted sesame seeds & sliced green onions along with the reserved sauce on the side. Enjoy.