||To cook the quinoa: rinse the quinoa thoroughly. In a medium saucepan bring the water and quinoa to a boil. Cover, reduce the temperature to a simmer and cook for 10 minutes. Turn off the heat and leave the saucepan to sit for a further 4 minutes. Fluff the quinoa with a fork and then allow to cool.
||Using a food processor combine the beef, onion, garlic and mushrooms. Pulse until thoroughly combined and scoop into a bowl.
||Stir through the egg, cooked quinoa, and mustard. Use your hands to thoroughly mix the ingredients together. Shape into small teaspoon-sized balls and set aside.
||Heat oil in a large frying pan over medium heat. Add the balls in batches and turn to brown all over. Once cooked through, remove from the pan and freeze separately.