In a mixing bowl, combine flour, sugar, and yeast.

Add warm water and vegetable oil, mix until a dough forms.

Knead the dough for about 10 minutes until smooth.

Let the dough rise for 1 hour in a warm place.

In a bowl, mix sweetened condensed milk and sugar until well combined.

Divide the dough into small pieces and flatten each piece.

Place a spoonful of filling in the center and fold the dough over.

Steam the buns for 15 minutes until cooked through.