In a large bowl, combine soy sauce, white vinegar, water, and keto-friendly sweetener. Stir until the sweetener is dissolved.
Add chicken thighs to the marinade, making sure they are submerged. Let marinate for at least 30 minutes, or for better flavor, refrigerate and marinate overnight.
In a large skillet or Dutch oven, heat avocado oil over medium heat. Add garlic and onions, sautéing until onions become translucent and garlic is fragrant, about 3-4 minutes.
Remove the chicken from the marinade (keep the marinade) and add to the skillet. Sear chicken on both sides until browned, about 5 minutes per side.
Pour the reserved marinade over the chicken. Add bay leaves and peppercorns.
Bring the mixture to a boil, then reduce heat to a simmer. Cover and cook for 30 minutes, or until the chicken is cooked through and tender.
Remove the bay leaves and increase heat to reduce the sauce to your desired thickness, about 5-10 minutes.
While the chicken is cooking, heat coconut oil in a separate pan over medium heat.
Add the riced cauliflower and a pinch of salt. Stir to coat evenly with oil.
Cover the pan and cook for about 8 minutes, stirring occasionally, until the cauliflower is tender but not mushy.