Tomato-crust potatoes - Tony Kitous

Ingredients

• 4 tbsp olive oil
• 1 large onion, thickly sliced
• good pinch of salt
• 2 garlic cloves, crushed
• 750g waxy potatoes, such as Desiree or Marfona
• 1kg large tomatoes, sliced
• 300ml hot lamb or vegetable stock, plus a little extra
• 2 tsp dried thyme
• ½ tsp ground cinnamon
• handful of mint leaves, roughly chopped
• salt and freshly ground black pepper