Sweat the onion: Heat the olive oil in a small frying pan over medium heat. Add the diced onion and cook for 3–4 minutes, stirring occasionally, until it turns translucent and smells sweet — you'll notice a gentle golden colour forming at the edges.

Bloom the garlic: Stir in the minced garlic and cook for another 30 seconds, just until it becomes fragrant — that sharp, earthy aroma means it's ready. Do not let it burn.

Build the sauce: In a large bowl, whisk together the tomato passata, chicken stock, apple cider vinegar, Worcestershire sauce, brown sugar, smoked paprika, mustard powder, salt, and pepper. The mixture should look deep red and smell tangy and smoky.

Layer the chicken: Place the chicken thighs in the bottom of the slow cooker in a single layer, if possible. Spoon the cooked onion and garlic over the top.

Pour the sauce: Pour the sauce mixture over the chicken, ensuring each piece is mostly submerged. The liquid should come about three-quarters of the way up the chicken — if not, add a splash more stock.

Slow cook: Cover and cook on low for 6–7 hours, or on high for 4 hours. After 4 hours on high, the chicken should be fork-tender — when you press it with a spoon, it should shred easily without resistance.

Shred the chicken: Using two forks, shred the chicken directly in the slow cooker. The meat should pull apart into thick, juicy strands — if it feels dry, stir in an extra 50 ml of stock.

Thicken the sauce (optional): If you prefer a thicker sauce, remove the lid and cook on high for another 15–20 minutes. The liquid will reduce and become glossy, coating the back of a spoon.

Rest before serving: Let the shredded chicken sit in the sauce for 5 minutes off the heat. This resting time allows the flavours to meld and the meat to soak up all that smoky goodness.