Start by mixing all the sauce ingredients together in a small bowl and set aside.
Heat the olive oil in a pan over medium heat. Add the ginger, garlic, and white parts of the green onions. Cook the mixture until you can start to smell it, which will take about 1 minute.
Add the chicken to the mixture and cook for 4-5 minutes. The chicken should be almost cooked all the way, but not quite. Add the bell pepper and sauce. Cook the mixture for 3-4 minutes, until the sauce is thick and the chicken is fully cooked.
Serve by adding 1/4 cup of the mixture into a lettuce leaf. Add scallions and yum yum sauce on top.