Cut chicken into bite-sized pieces. Dip in egg then roll in flour to coat pieces.
Add oil to a heavy skillet, turn to medium-high heat. Add a small pinch of flour to the oil. If it sizzles, it's hot enough.
Cook just until golden on all sides. Do not cook all the way through.
Remove skillet from heat and place chicken on a paper towel to drain off any excess oil.
Add all sauce ingredients to a mixing bowl. Whisk until combined.
Add chicken and sauce to a slow cooker. Cook on high 1.5-2 hours or low 3-4 hours.
Add to serving dish and garnish with green onions.