- Preheat sous vide machine to 68C.
- Place all the ingredients except brisket in a large bowl. Add 1 litre water and whisk to combine.
- Transfer mixture to a large sous vide bag. Add brisket and seal bag, removing all air.
- Place bag in sous vide machine and let cook for 24 hours.
- Remove bag from water and set aside in fridge to cool until serving.
- Place egg, Dijon mustard, white wine vinegar, garlic and salt in a small food processor or the canister of a stick blender. Blend until well combined. With the machine running, very slowly add grapeseed oil, and continue to blend until mixture is thick and creamy. Transfer mayonnaise to a small bowl.
- Add seeded mustard to the mayonnaise and stir to combine. Transfer to a squeeze bottle or piping bag and set aside, in fridge, until serving.
- Place sugar and vinegar in a medium saucepan and set over low heat. Heat until mixture is at a gentle simmer and sugar has dissolved.
- Add onion and cook gently, stirring frequently, until onions have softened but not taken on any colour, about 3-5 minutes. Remove from heat and set aside until serving.
- Preheat BBQ to high heat.
- Remove brisket from fridge, remove from liquid and pat dry.
- Cut brisket into thick slices and place on BBQ to cook until brown and caramelized. Remove from heat.
- Lay pita bread out on bench top.
- Squeeze some Mustard Mayo onto each pita bread followed by Red Onions. Add a slice of barbequed Brisket and top with parsley leaves and radish slices.
- Roll pita breads and place into serving wrappers