Heat the milk over medium heat with the cinnamon stick, lemon peel, and sugar. Let it infuse for about 30 minutes. Remove from heat and let cool completely.

Place the donuts in a deep dish and soak them for 2 hours, turning them every 30 minutes.

Let the donuts drain on a wire rack.

In a shallow bowl, mix the sugar with the ground cinnamon.

Fry the donuts in plenty of vegetable oil until golden brown. Remove and coat them in the cinnamon sugar mixture.