Place the chicken tenderloins in the bottom of the slow cooker in a single layer.
In a medium bowl, whisk together the chicken broth, honey, soy sauce, Dijon mustard, olive oil, minced garlic, dried thyme, black pepper, salt, and smoked paprika until well combined.
Pour the sauce mixture evenly over the chicken tenderloins in the slow cooker.
Scatter the thinly sliced onion over the chicken and sauce.
Cover the slow cooker with the lid and cook on low for 3 to 3.5 hours, or until the chicken is cooked through and tender.
About 15 minutes before serving, remove the chicken tenderloins and keep warm on a plate covered with foil.
In a small bowl, mix the cornstarch and cold water to create a slurry.
Pour the slurry into the slow cooker and stir gently to combine with the cooking liquid.
Turn the slow cooker to high and cook uncovered for 10 to 15 minutes until the sauce thickens.
Return the chicken tenderloins to the slow cooker and coat with the thickened sauce.
Serve the chicken tenderloins hot with the sauce spooned over the top.