Salt and pepper both sides of the chicken breasts and place them in crock pot. In a small bowl, combine honey, soy sauce, onion, ketchup, oil, garlic and pepper flakes. Pour over chicken. Cook on low for 3 to 4 hours or on high 1 1/2 – 2 1/2 hours, or just until chicken is cooked through. Use a slotted spoon to remove chicken to a plate or cutting board, leaving the sauce.
In a small bowl, whisk together 4 teaspoons of cornstarch in 6 tablespoons of cold water (or just enough to dissolve the corn starch, it's up to you). When all the lumps are gone, pour it into crock pot. Stir to combine with sauce. Put the lid back on and cook sauce on high for ten more minutes or until slightly thickened.
When the chicken is cool enough to handle, cut or shred the chicken into bite size pieces, then return to pot and toss with sauce before serving. Add a dash or two of Sriracha sauce. Sprinkle with sesame seeds and serve over rice or noodles.