Slow cooked Greek greens

Name: Slow cooked Greek greens
Ingredients: 4–5 tbsp extra virgin olive oil, plus extra for serving; 3 onions, sliced; 3 carrots, peeled and sliced into 1cm/½in rounds; 4 garlic cloves, finely chopped; 1 tbsp tomato purée; 400g tin chopped tomatoes (or 400g/14oz fresh, ripe tomatoes, roughly chopped); 500ml/18fl oz vegetable stock; 600g/1lb 5oz green beans or runner beans (or a mixture of both), trimmed and cut into halves or thirds; salt and freshly ground black pepper; 15g/½oz mixed fresh soft herbs (I like dill and flatleaf parsley), finely chopped, to serve; fresh bread, to serve; capers, to serve (optional)