First make your tomato based stock. Take a sieve and strain the tins of chopped tomatoes over a bowl. Use a spoon to mush the tomatoes left in the sieve to a fine pulp, then pour this pulp back into the tomato juice in the bowl. Add in the vegetable stock and tomato puree and stir. Heat this stock in a small pan or in the microwave until almost boiling, then turn off the heat.
Heat oil in a large pan, add the onion and cook for about 5 minutes until the onion starts to go translucent, add in the garlic, stir and cook for a further minute. Add in the rice and stir until the oil has coated the rice. Add in the wine and stir. Wait for the wine to almost fully absorb (stirring regularly) and then add the tomato stock a ladle at a time. Ensuring each ladle has almost fully absorbed before adding the next. Ensure you stir regularly. This should take for 15-20 mins. Once you've used up all the stock, have a taste of the rice. It should be soft, but still have a bit of a bite to it (it will soften up a little further when you add the cream). If the rice is still far too hard, you can add in a ladle or so of water. When the rice is cooked, add in the cream, cheese, lemon juice and salt & pepper. Stir and then turn off the heat. Leave to cool in the pan, then cover with clingfilm (plastic wrap) and refrigerate for 30 minutes (or up to 2-3 days).
When you're ready to make your arancini put the beaten eggs, breadcrumbs and flour on 3 large plates.
Take the cold risotto out of the fridge and take a heaped tbsp. of the of the rice in your hand. Flatten it out and then place a tsp of boursin cheese in the centre. Wrap the risotto around the cheese and roll into a ball. Place the ball onto a plate and repeat until you've used all of your mixture.
Fill a large heavy-bottomed saucepan with the vegetable oil until it's about 1/3 full. There needs to be enough oil to completely cover the Arancini. Heat the oil on high.
Now dip each arancini ball in turn into the flour, egg and finally the breadcrumbs, shaking off any excess as you go.
Check the heat of the oil by dropping in a few of the panko breadcrumbs. If they immediately rise to the top and bubble vigorously, then the oil is ready. Turn it down to medium-high and carefully place in 3-4 arancini balls in the oil. Cook for 2 minutes until the Arancini is golden brown, then remove from the oil with a slotted spoon and place on a wire rack with some kitchen paper underneath to drain. Repeat until all of the arancini is cooked.
If you're serving straightway, the Arancini should still be hot enough. Alternatively you can keep them warm in a low oven for 15 minutes or so until you're ready to serve.
You can make these arancini balls in advance and then reheat them in the oven. They're not quite as good as when they're freshly cooked from the pan, but they're still crisp and delicious. Simply allow the arancini to cool, then cover and refrigerate. Reheat in the oven for 15 minutes at 200c/400f..Nutritional Information is per serving, (accounting for 2 tbsp of oil being absorbed during the cooking of all arancini).