In a bowl, mix warm water and condensed milk. Add yeast and let it sit for 5 minutes.
Add an egg to the mixture and stir well.
Gradually add all-purpose flour and salt, mixing until the dough comes together.
Knead the dough on a floured surface until smooth and elastic, adding more flour if necessary.
Cover the dough and let it rest for 45 minutes, or until doubled in size.
Once risen, shape the dough into small balls. Dust with additional flour to prevent sticking.
Let the balls sit for 10 minutes before frying.
Fry the donut balls until golden brown and cooked through, about 3-5 minutes per batch.
Drain excess oil on paper towels and serve hot.