1. In a medium bowl, whisk together the hoisin sauce, soy sauce, garlic, rice vinegar, sugar-free honey, five-spice powder, salt, and red pepper flakes. Remove 1/4 cup marinade and set it to the side.
2. Add the chicken to the remaining marinade and toss to coat. Cover and let sit for at least 30 minutes at room temperature or up to 24 hours in the refrigerator.
3. Prepare a grill for medium-high heat; preheat for 5 minutes. Lightly brush grates with oil.
4. Remove chicken from marinade and grill, turning once and brushing with reserved 1/4 cup marinade, until cooked through and an instant-read thermometer inserted into the thickest part registers 165°, 8 to 10 minutes (these thighs are very forgiving; you can continue to grill until more fat renders and thermometer registers 175° to 180° if desired).

For the Pickled Vegetables

1. Place carrot and cucumber in a fine-mesh strainer. Sprinkle with salt and 1 teaspoon sweetener and gently massage into vegetables until softened about 3 minutes. Transfer to a medium heatproof bowl.
2. In a small pot over medium-high heat, heat water, vinegar, and remaining 1/4 cup sweetener, stirring, until sugar is dissolved and the mixture is steaming, 1 to 2 minutes. Pour hot pickling liquid over vegetables and stir to coat. Cover and let sit for at least 1 hour or up to 1 week.

To Serve

1. Place chicken in a keto taco shell, over lettuce or over riced cauliflower.  Top with pickled vegetables and any other sauces.