Finely chop the onion (1 onion)
Heat the olive oil (2 tsp) in a large saucepan.
Once the oil is hot, add the chopped onion and cook on a low heat for 5 minutes, stirring regularly.
While the onion is cooking, peel and finely slice the garlic (2 cloves), roughly chop the peppers (1 red, 1 green) and chop the green beans into 3 (remember to discard the nasty ends!)
Add the peppers, garlic, paprika (1 tsp), ground cumin (1 tsp) and hot chilli powder (½ tsp) to the pan and cook for a further 5 minutes stirring regularly.
While the peppers, etc. are cooking, peel the sweet potato (1 medium potato) and chop it into cubes (about 1½-2cm cubes).
Add the sweet potato, dried oregano (½ tsp), instant coffee (½ tsp), chopped tomatoes (400g can), tomato purée (1 tbsp) and vegetable stock (300ml, or 300ml water and a vegetable stock cube). Bring to the boil, then simmer for 20 minutes.
Drain the mixed beans (400g can) and add them to the pan. Simmer for a further 10 minutes.
Season with salt and pepper and serve.