Fry the onions and garlic in a bit of oil and the butter. Just before they start to colour, add your rice and thyme. Fry that for 1 minute (it can stick!). Now start adding the stock. You want to be adding about 1 cup every 3 minutes. Do not stop stirring the rice! The idea is to let all the stock be absorbed, then add more. Try to soak up all the stock over 15 or so minutes. This is the real challenge. Not too hot, not too fast, not too cold, not too slow. When the rice is nice and firm, with no hard core in the middle of the grain, remove from the pot and spread over a tray, to cool it quickly. A nice breezy place is great.
Mix all the cheese, zest and juice together.
Get your now warm rice back in a big pot and mix it with the cheese and herbs.
Taste it and add salt and pepper where needed. Wipe out the small pot (no need for excess dishes) and put the rice flour in.
With slightly wet hands, form the warm mix into golf balls, cover and roll back into golf balls. Dust in rice flour and fill that tray. Cover in cling film and refrigerate. When it's serving time just fry them in some hot vegetable oil, about 5 minutes. You can deep fry or shallow fry.