Rinse 1 cup of rice under cold water until the water runs clear.
Cook the rice with 1 1/2 cups water in a covered pot over low heat for 15 minutes.⏱ 15 min
Whisk soy sauce, brown sugar, sesame oil, and minced garlic together in a small bowl.
Heat cooking oil in a large skillet over medium-high heat until shimmering.
Add the sliced vegetables and stir-fry for 3 minutes until crisp-tender, then set aside.⏱ 3 min
Add the beef to the hot skillet and cook for 5 minutes until browned throughout.⏱ 5 min
Pour the sauce mixture over the beef and cook for 2 minutes until glossy and fragrant.⏱ 2 min
Arrange clean lettuce leaves on a platter alongside bowls of rice, beef, and vegetables.
Spoon warm rice into a lettuce cup, top with beef and vegetables, and wrap to eat.