How to Make It
Heat 1 tablespoon of the canola oil in a large skillet over medium-high heat. Add the scallions and ginger and cook, tossing, until softened, 2 to 4 minutes. Add the beef and cook, breaking it up with a spoon, until browned, 3 to 5 minutes. Add the soy sauce, tomato paste, sugar, ¼ teaspoon pepper, and ½ cup water and cook, stirring, until slightly thickened, about 1 minute more.
Toss cabbage, carrots, cilantro, lime juice, sesame oil, the remaining tablespoon of canola oil, and ¼ teaspoon each salt and pepper in a large bowl.
Fill the buns with the meat, dividing evenly, and serve with the slaw and lime wedges.