Fry shallot and garlic in butter for 5 minutes until softened.
Add thyme and mushrooms and fry for 2 minutes.
Stir in rice to coat and add wine to bubble for 1 minute.
Add 600ml stock gradually by ladlefuls, stirring until absorbed and rice is creamy.
Stir in mascarpone, Parmesan, and parsley, then cool.
Sear seasoned beef in hot olive oil for 3 minutes until brown.
Wrap beef tightly in cling film and refrigerate for 1 hour.
Cover each mozzarella ball with cooled risotto and shape into balls.
Fry risotto balls at 180°C for 5 minutes until golden and drain.
Pound green sauce ingredients into a thick paste using a mortar.
Slice beef thinly and serve with green sauce, risotto balls, rocket, and Parmesan.