Vegetable garden risotto

Name: Vegetable garden risotto
Ingredients: 250g/10oz broad beans; 50g/2oz butter; 3 tbsp olive oil; 1 tbsp chopped fresh mint leaves; 1 onion, finely chopped; 2 garlic cloves, crushed; 3-4 sprigs fresh thyme; 1 long strip lemon zest; 1 bay leaf; 150g/5oz arborio risotto rice; 150ml/5oz dry white wine; 750ml/1 pint 7fl oz hot vegetable stock; 100g/3½oz peas; 1 bunch asparagus, trimmed and cut into short lengths; 100g/3½oz fresh runner beans, de-stringed and cut into long thin strips; 100g/3½oz feta cheese, drained and crumbled into small pieces; Sea salt flakes and freshly ground black pepper; Parmesan shavings, to serve