Sear the steak. Heat the oil over medium-high heat in a large, heavy-bottomed skillet. Add the beef, season with salt and pepper, and saute until caramelized. Add the whites of the scallions and saute for 30 more seconds. Turn off the heat.

Make the sauce. Whisk together the soy sauce, honey, garlic powder, onion powder, toasted sesame oil, rice wine vinegar, ground ginger, and red pepper flakes.

Load the crock pot. Add the beef to the basin of your crock pot and pour the sauce over it. Stir until the meat is thoroughly coated in the sauce.

Slow cook. Seal the crock pot and cook on high for 3 hours.

Thicken the sauce. Use a slotted spoon to transfer the beef to a large mixing bowl. Pour the juices in the crock pot into a saucepan. In a small bowl, whisk together ¼ of the sauce with the cornstarch until smooth. Pour that into the rest of the sauce. Cook the sauce over medium-high heat, stirring consistently, until thickened.

Put it all together. Pour the sauce over the beef and toss to coat.

Serve. Serve over rice garnished with the greens of the scallions.