Preheat oven to 150°C (130° fan-forced). Wash beef and pat dry with paper towel. Place onions in centre of an ovenproof casserole dish and place beef on top, fat side up. Sprinkle top of beef with sugar and add bay leaves and peppercorns to dish. Pour beer and stock around beef, ensuring the liquid covers beef. Cover and place in oven for 1 ½ hours or until cooked to your liking. Remove beef from liquid and set aside on a plate loosely covered with foil to rest for 10 minutes.
Meanwhile, in a large bowl place zucchini, peas, egg, flour, haloumi and mint. Season and stir well to combine. Heat oil in a large non-stick frying pan medium heat. Spoon ¼ cup portions of zucchini mixture into pan and cook, in batches, for 3-4 minutes each side until golden. Set aside on a plate lined with paper towel. Repeat with remaining zucchini batter.
Slice corned beef and serve with fritters, sweet potato mash, baby spinach, tzatziki and mint leaves.
The longer you cook the corned beef the more tender it will become – for pull apart corned beef cook for 3-4 hours.
Use leftover corned beef to make healthy Reuben sandwiches with coleslaw and yoghurt dressing, corned beef hash or even a corned beef potato salad.
Swap beer for more stock, if desired; swap peas for corn kernels; serve with pre-made gravy instead of tzatziki, if desired.