Cook the rice according to package instructions.
In a large skillet over medium-high heat, add ground beef and diced onion. Cook until browned and onions are translucent, about 5-7 minutes.
In a small bowl, whisk together soy sauce, brown sugar, pressed garlic, minced ginger, sesame oil, garlic powder, onion powder, and red pepper flakes. Pour over the beef and onion, stirring well.
Mix corn starch and water until smooth. Add to the skillet, stirring until the sauce thickens, about 2-3 minutes. Remove from heat.
In a large bowl, combine coleslaw mix, shredded carrots, and sliced cucumber. Toss to mix.
Assemble the bowls with a scoop of rice, topped with the beef mixture and fresh vegetables. Drizzle with spicy mayo and yum yum sauce.
Serve immediately, garnished with additional crushed red pepper flakes or sesame seeds if desired.
