Combine the milk, water, 60 g sugar, salt, lemon zest, and orange zest in a 3-quart / 2.8 L saucepan. Bring to a gentle simmer over medium heat.

Stir in the rice, lower the heat, and cook uncovered for 25 to 30 minutes, stirring often, until the rice is very soft and the mixture looks like thick porridge.

Stir in the vanilla extract, then spread the rice mixture onto a sheet pan or wide shallow dish to cool. Let it come to room temperature, then refrigerate uncovered for at least 1 hour, until fully cold.

Transfer the cold rice to a large mixing bowl. Beat in the eggs one at a time, mixing well after each addition.

Add the flour, baking powder, and rum. Mix until you have a thick, sticky dough that holds its shape on a spoon.

Pour the frying oil into a 24 cm / 9.5-inch deep pot or dutch oven to a depth of about 5 cm / 2 inches. Heat to 170C / 340F, checking with a deep-fry or instant-read thermometer.

Scoop rounded tablespoons of batter (a spoon dipped in water helps it release) and slide them gently into the oil, frying 5 to 6 at a time so the temperature doesn't drop.

Fry for 3 to 4 minutes, turning occasionally with a slotted spoon, until deep golden brown and cooked through in the center.

Lift the fritters out with the slotted spoon and drain briefly on paper towels.

While still warm, roll each fritter in the remaining 100 g sugar to coat.

Let the oil return to 170C / 340F between batches and repeat with the rest of the batter. Serve warm.