Slow-cooked chickpeas with rosemary, sun-dried tomatoes and honey

300g (1 1/3 cups) dried chickpeas (garbanzo beans) (or 2 x 400g/14oz cans of cooked chickpeas, drained and rinsed)
4 tbsp extra virgin olive oil, plus extra to serve
1 onion, finely chopped
2 garlic cloves, minced
1 large fresh rosemary sprig (or 1 tsp dried rosemary)
80g (½ cup) sun-dried tomatoes, drained and chopped
2 tbsp Greek honey
400ml (1¾ cups) vegetable or chicken stock (or water)
Juice of ½ lemon, or to taste
Sea salt and freshly ground black pepper