Set a large pan, at least 3 inches deep, over medium-low heat with about 2 inches of oil. You're just getting a head start on warming it up.
Make sure the rice is cold or at least room temperature. If it's hot, the sugar will dissolve into it, and the calas won't hold together. Working with a spoon or your fingers, break the rice up in a large bowl so there are no clumps. If you're not using an oil thermometer, take out a few grains, maybe 5 or 6, and reserve them. Add all the dry ingredients and mix them well into the rice; as you do so, the powders will stick to each grain making them look cartoonishly fat. It's kind of a strange, wonderful sight. (Or unnerving, if you were traumatized as a child like I was by the movie "Poltergeist.")
Crack in the eggs and vanilla and mix them in thoroughly, so there are no dry spots. Poppy uses a smearing motion with the back of the spoon to make sure the egg is totally incorporated. This is your batter. That's it. Easy, huh?
Check your oil. If you have a thermometer, you want it to be about 360 degrees. If not, drop in a grain of rice. It should be just hot enough to make that rice pop right up and sizzle immediately, but it shouldn't be incinerating it. Adjust the flame to get the oil to the right temperature, and then turn it to medium.
Form the calas into quenelles with two large tablespoons (here's a video for the method) and drop them in by tipping the head of the spoon toward the oil and pushing the batter off from the back, rounding it into a cute egg shape. When the calas go in the oil, they should sink to the bottom and the heat should be enough to make them come right back up, carried on a float of sizzling bubbles.
"It's an obedient food," Poppy says. By that she means that once one side has puffed and browned, it will roll itself over and the bottom will cook. If they don't, though, give them a gentle nudge. Work in batches, being sure to give them plenty of room to float around. Fry them until they are the color of good donuts, just past golden brown, but not much darker.
Remove them with a slotted spoon or tongs, drain them well on several sheets of paper towel, and dust them generously with powdered sugar. Serve hot, calling, "Belle calas, tout chaud!"
Francis Lam is Features Editor at Gilt Taste, provides color commentary for the Cooking Channel show Food(ography), and tweets at @francis_lam.