General tips
Toast the rice in butter before bagging. Risotto rice needs that initial toasting to crack open the outer starch layer - without it, you get glue, not creamy risotto. Two minutes in a hot pan with a tablespoon of butter, until the grains smell nutty.
Use Arborio, Carnaroli, or Vialone Nano. Long-grain rice doesn't have the starch content to make risotto - it'll just be mushy boiled rice. The Italian short-grain varieties are the only ones that release the starches that create creaminess.
Hot stock, not cold, into the bag. The bath holds at 197°F, and adding cold stock means the rice has to fight to come up to temperature. Pre-warm the stock to a simmer, deglaze the toasted rice, then bag everything together while it's still hot.
45 min is the magic number. Less and the grains are still chalky in the center; more and the starch has fully released and you've got porridge. The 45-minute mark gives you al dente grains with a creamy emulsion. Time it precisely.
Anti-tip: don't add the cheese in the bag. Parmesan, butter, and any fresh herbs go in AFTER the rice comes out of the bath, stirred vigorously off-heat. Adding cheese in the bag turns it stringy and makes the texture grainy. Stir it in at the end like a real risotto.
Creamy tips
Shake jars vigorously right after cooking to release starch and keep grains loose.
Add a splash of hot stock in a skillet to loosen before serving; the starch tightens as it cools.
Season lightly in the jar and adjust salt after finishing to avoid overseasoning.
Sliceable tips
Line a sheet pan with parchment, spread the hot risotto, and chill quickly before portioning.
Keep your hands wet when forming arancini to prevent sticking.
Double-coat in breadcrumbs for extra crunch if frying.