Combine flour and pepper in large Ziploc bag. Add chicken. Shake to coat with flour mixture. Heat oil in skillet over medium-high heat. Brown chicken about 2 minutes on each side. Place chicken in slow cooker.
Combine soy sauce, vinegar, ketchup, sugar, garlic, ginger, and pepper flakes in small bowl; pour over chicken. Cook on LOW for 3 to 4 hours. Add cashews and stir. Serve over rice.
If you want extra sauce to pour over the chicken and the rice, double the sauce ingredients.
I also will dice celery, carrots, onions to put in the pot with the chicken. What goes in the pot depends on what I have on hand and my mood. Make sure it is a small dice so the veggies cook to a tender state.