Spicy meatballs with chilli black beans

Name: Spicy meatballs with chilli black beans
Ingredients: 1 red onion, halved and sliced; 2 garlic cloves, sliced; 1 large yellow pepper, quartered, deseeded and diced; 1 tsp ground cumin; 2-3 tsp chipotle chilli paste; 300ml reduced-salt chicken stock; 400g can cherry tomatoes; 400g can black beans or red kidney beans, drained; 1 avocado, stoned, peeled and chopped; juice ½ lime; 500g pack turkey breast mince; 50g porridge oats; 2 spring onions, finely chopped; 1 tsp coriander; small bunch coriander, chopped, stalks and leaves kept separate; 1 tsp rapeseed oil