Korean Bulgogi Bowl

Name: Korean Bulgogi Bowl
Ingredients: 1 pound lean ground beef; 1 tablespoon sesame oil; 0.25 cup brown sugar; 0.25 cup soy sauce; 0.25 cup water; 0.5 Asian pear, grated; 5 cloves garlic, minced, or more to taste; 1 inch piece ginger, peeled and diced; 1 teaspoon red pepper flakes; 0.5 teaspoon ground black pepper; 1 cup cooked brown rice, or more to taste; 1 head romaine lettuce, chopped, or to taste; 1 cucumber, diced; 1 red bell pepper, diced, or to taste; 1 tablespoon sesame seeds, or to taste