Prepare the Base: Place the chopped onion and minced garlic in the bottom of your slow cooker pot. This creates a flavourful bed for the chicken to cook on.

Add the Chicken: Lay the chicken breasts on top of the onions and garlic in a single layer.

Mix the Sauce: In a medium bowl, whisk together the chopped tomatoes, chicken stock, chipotle paste, tomato purée, smoked paprika, ground cumin, dried oregano, salt, and pepper until well combined.

Pour and Cook: Pour the sauce mixture evenly over the chicken breasts in the slow cooker. Ensure the chicken is mostly submerged.

Slow Cook: Cover the crockpot and cook on LOW for 5-6 hours or on HIGH for 3-4 hours. The chicken is done when it is cooked through and very tender. You can check the internal temperature has reached at least 74°C (165°F) for safety, as recommended by the Food Standards Agency.

Shred the Chicken: Carefully remove the cooked chicken breasts from the slow cooker and place them on a large plate or cutting board. Using two forks, shred the chicken. I find it shreds almost effortlessly when it's properly cooked.

Finish the Sauce: Stir the fresh lime juice into the sauce remaining in the crockpot. Give it a taste and adjust seasoning if needed.

Combine and Serve: Return the shredded chicken to the slow cooker and stir it into the sauce until it's fully coated. Let it sit for 5-10 minutes to absorb all the flavours. Serve the shredded chicken taco meat warm in tortillas with your favourite toppings, like chopped coriander, diced avocado, and a dollop of soured cream.