Sneaky Rissoles on Potato and Leek Smash

Name: Sneaky Rissoles on Potato and Leek Smash
Prep time: 20 min
Cook time: 40 min
Total time: 1 h
Ingredients: 500g beef mince; 500g pork mince; 1 onion, finely chopped; 1 large courgette, grated; 1 cup grated peeled beetroot; 1/2 cup dried breadcrumbs (or 2 slices whole meal toast bread processed to a crumb); 1 large free range egg; 1/2 cup chopped fresh herbs (parsley, chives, sage); 1/4 cup tomato paste; 1 tbsp extra virgin olive oil; 2-3 cloves garlic, crushed; 1 tsp ground black pepper; 1 tsp Worcestershire sauce; 1/2 tsp salt; Olive oil for cooking; 1 1/2 cups reduced salt beef stock; 3 tbsp tomato relish; 2tsp cornflour mixed with 2tsp water; 1kg floury potatoes (such as agria), scrubbed and halved; 50g butter; 1 leek, finely chopped; 1/4 cup finely chopped fresh chives or parsley; 1 tbsp Dijon mustard; Freshly ground black pepper; Squeeze of lemon