Heat the vegetable oil in a large Dutch oven or heavy-bottomed pot over medium-high heat. Brown the chicken thighs in batches, about 3-4 minutes per side until they develop a golden crust. Remove the chicken and set aside.
In the same pot, add the ground beef, breaking it up with a wooden spoon. Cook until browned, approximately 5-7 minutes. Drain excess fat if needed, but leave about 2 tablespoons in the pot.
Add the diced onions and bell pepper to the pot. Cook for 5-6 minutes until they begin to soften and turn translucent. Stir in the garlic and cook for another 30 seconds until fragrant.
Return the browned chicken to the pot. Add the lima beans, corn, diced tomatoes, and potatoes. Pour in the chicken stock, barbecue sauce, Worcestershire sauce, and apple cider vinegar.
Stir in the brown sugar, smoked paprika, dried thyme, cayenne pepper, salt, and black pepper. Bring the mixture to a boil, then reduce heat to low. Cover and simmer for 1.5 hours, stirring occasionally to prevent sticking.
After 1.5 hours, uncover the pot and increase heat slightly to medium-low. Allow the stew to simmer for an additional 30 minutes, or until it reaches your desired thickness. If you prefer a thicker consistency, you can mash some of the potatoes against the side of the pot. Taste and adjust seasonings as needed.