Heat olive oil in a large skillet over medium heat.
Add diced onion and sauté for 2-3 minutes until softened.
Stir in minced garlic and grated ginger, cooking for another minute.
Add ground beef and cook, breaking it apart, until browned and fully cooked.
Drain excess grease if necessary.
Stir in soy sauce, hoisin sauce, rice vinegar, sesame oil, and red pepper flakes. Cook for an additional 2-3 minutes, allowing flavors to blend.
Remove from heat and stir in chopped green onions.
Spoon the beef mixture into lettuce leaves.
Top with shredded carrots, sesame seeds, and chopped cilantro if desired.
Serve immediately and enjoy!