In a small bowl, combine hoisin sauce and soy sauce with 1/3 cup water

In a large skillet or wok, heat 1 tbsp oil over medium-high heat. Add chicken and cook, breaking apart with a wooden spoon, until browned, 4 min.

Reduce the heat to medium, add the carrot and the remaining 1 tbsp oil and cook, stirring, 2 min. Add the garlic and scallion whites and cook 1 min. Stir in the hoisin mixture and cook until sauce thickens and coats the chicken and vegetables, 1-2 min.

Divide the lettuce leaves among 4 plates. Top each leaf with the chicken mixture; sprinkle with the scallion greens.