Stuffed cabbage leaves - River Cottage

Ingredients

• 12 outer leaves from a large Savoy cabbage
• 4 tablespoons soured cream, plus extra to serve (optional)
• For the tomato sauce
• 2 tablespoons olive oil
• 1 onion, chopped
• 1 bay leaf
• A couple of sprigs of thyme
• 1 carrot, chopped
• 1 celery stalk, chopped
• 2 garlic cloves, finely chopped
• 600g fresh, ripe tomatoes, skinned and chopped, or a 400g tin plum tomatoes, roughly chopped, any stalky ends and skin removed
• A pinch of sugar (optional)
• Sea salt and freshly ground black pepper
• For the filling
• 120g pearled spelt, rice or pearl barley
• 1 tablespoon olive oil
• 1–2 garlic cloves, finely chopped
• 50g currants
• 50g walnuts, roughly chopped
• Finely grated zest of 1 lemon
• A bunch of parsley, chopped
• A handful of dill, chopped
• ¼ teaspoon dried chilli flakes
• 1 large egg, lightly beaten