Wash the beans, top, tail and string them where necessary.
Heat the oil in a large heavy-lidded pan and add the onions and garlic. Cook for 2-3 minutes to soften. Add the beans in their pods and the lemon juice and toss to combine.
Add the stock, bring to the boil and cook for 20-25 minutes until the pods are very tender. Cover and reduce heat to a gentle simmer.
At the end of cooking, add the dill. Serve warm. Add a generous dollop of Greek-style yoghurt (optional).