Heat the oil in a shallow saucepan or casserole dish with a lid. Tip in the onions and cook over a medium-low heat for 5 mins until softened. Add the chicken and turn up the heat to medium. Stir in the garlic, a small pinch of sugar, the oregano, cumin seeds and some seasoning. Cook for a couple of minutes, then add the chipotle and cook for a few minutes more. Pour in the passata, 100ml water and add the stock. Season and bring to a simmer.
Cover with a lid and cook for 40-50 mins, stirring occasionally until the chicken is tender. Shred the chicken into the sauce using two forks, then stir through the beans. Simmer for 5 mins more, then turn off the heat. Squeeze in the lime juice. Can be kept chilled for three days and frozen for up to two months. Defrost thoroughly and reheat. Serve with rice or tortilla wraps, and some coriander, feta, lime wedges and red onion on the side, if you like.
