In the slow cooker, whisk together the coconut milk, red curry paste, creamy peanut butter, soy sauce, honey, rice vinegar, minced ginger, minced garlic, and finely diced onion until smooth.
Add the bite-size chicken pieces and diced red bell pepper to the sauce in the slow cooker, then stir to fully coat the chicken and pepper.
Cover and cook on LOW for 3 to 4 hours, or until the chicken is cooked through and tender.
Stir the cooked mixture, taste and adjust seasoning if desired, then serve over rice or with naan and optional scallion rings and a squeeze of fresh lime.