For the risotto, melt butter and oil in a large pan over a mode rate heat and cook the onion for 3 - 4 minutes until softened.
Add rice and stir for 1 - 2 minutes to coat the grains.
Add the hot stock, a ladleful at a time and stir until liquid has reduced and is absorbed before adding the next ladleful of stock.
Continue until rice is tender, this will take about 20 minutes - you may not need all of the stock.
Remove from the heat, stir in the Parmesan cheese, lemon juice, zest and egg.
Season well with salt and pepper.
Chill for 30 minutes.
Coating and assembly
Place the flour, beaten eggs and bread crumbs into three separate shallow bowls.
Using your hands roll the chilled risotto into 16 balls - about 2 tab lespoons of mixture for each.
Make an indent in the centre of each with your thumb, add a piece of the Tussers Cheese, then reform into a ball around the filling.
Place on a tray.
First roll each ball first in flour and shake off excess, then egg, coat well with crumbs.
Chill for 30 minutes until firm.
Half-fill a deep-fryer with oil.
Heat the oil to 190°C and fry the risotto balls for 2 - 3 minutes until golden.
Drain on paper toweling and serve immediately.