Brown the ground beef in a skillet over medium-high heat. When the meat is halfway done cooking, add the grated ginger, minced garlic and whites of the scallion to the pan and stir to incorporate.
In a medium bowl, combine the soy sauce, brown sugar, sesame oil and the red pepper flakes. Stir to combine.
Once the ground beef mixture is fully cooked through, add the sauce to the pan and stir to coat evenly and incorporate all the flavors.
Serve in the lettuce cups with the green chopped scallions, toasted sesame seeds and matchstick carrots.
Notes
Note - you can make extra sauce to serve on the side. I would do 1/4 cup soy sauce, 1 tablespoon brown sugar, 1 teaspoon sesame oil and a dash of sriracha mixed together as a dipping sauce.