Combine cornstarch, salt, and pepper in small bowl. Gradually blend in water and egg yolks.
Pour oil into wok. Heat over medium/high until oil reaches 375 degrees. Dip chicken into cornstarch-egg yolk mixture. Fry in small batches until golden brown. Drain on paper towel and keep warm until you are finished cooking remaining chicken. You'll want to make sure the chicken internal temp is at least 165 degrees F.
Serve on top of rice and top with lemon sauce. Garnish with green onion.
For Sauce:
Combine all ingredients in medium saucepan, stir until blended. Cook over medium heat, stirring constantly, until sauce boils and thickens, about 5 minutes. Pour over chicken.