Vietnamese lamb shanks with sweet potatoes

Ingredients

• 2 tablespoons Ground Nut Oil
• 4 Lamb Shanks
• 2 Onion
• 2 tbs chopped Ginger
• 3 sliced thinly Garlic Clove
• 1 chopped Red Chilli
• 1 sliced Red Chilli
• 1 tablespoon Brown Sugar
• 1 tsp Brown Sugar
• 3 Star Anise
• 2 Lemongrass Stalks
• 1L Lamb Stock
• 1 ½ tbsp Tomato Puree
• 4 Sweet Potatoes
• 2 tablespoons Fish Sauce
• Juice of 2 Lime
• Handful Mint
• Handful Basil Leaves