Slow cooker sausage casserole - Good Food Middle East

Ingredients

• 2 red onions, finely chopped
• 1 celery stick, finely chopped
• 1-2 tbsp rapeseed oil
• 4 carrots, cut into fat pieces
• 12 chipolatas, each halved
• 1 sweet potato, peeled and cut into chunks
• 400g tin tomatoes
• 1 tbsp tomato purée or tomato and veg purée
• 1 thyme sprig
• 1 rosemary sprig
• 1 beef stock cube or stock pot