3/4cupsketo-friendly ketchup such as Alternasweetsor use 1/3 cup tomato paste and 1/2 cup monk fruit, golden with a few tablespoons water to thin the paste
Cook the chicken breasts either poached, sous vide, grilled, or pan seared.
While the chicken cooks, make the sauce. Add half a tablespoon of avocado oil to a small pot and when hot, add the onion. When the onion is softened and fragrant, about 5 minutes. Add all remaining ingredients then bring to a boil then reduce heat and simmer, uncovered until the sauce thickens. Taste and adjust seasoning with more salt, pepper, monk fruit, and vinegar to taste.
After the chicken is cooked, brush with the BBQ sauce and put them under the broiler for 2-5 minutes, until the sauce bubbles and caramelizes. Rest for at least 5 minutes before serving with the remaining sauce.