Place the barley in a saucepan and cover with cold water. Bring to the boil, then simmer for 35 mins until the barley is really tender. Rinse under cold running water, drain well and set aside.
Heat the olive oil in a saucepan and add the onion, leeks and carrot and cook for 4-5 mins. Add the garlic and tomatoes and cook for a further 3 mins.
Pour in the stock and bring to the boil. Reduce the heat and simmer for 10 mins. Add the cannellini beans, barley and cabbage and simmer for a further 5 mins. Stir through the pesto sauce and serve. For adults, serve with a sprinkling of Parmesan.