Take flour, salt, baking powder in a bowl and mix well. Set aside.
Take egg, sugar, milk, melted butter, vanilla in a bowl and whisk using a fork.
Now add the flour in and mix well using the fork. Knead to a soft dough.
Take the dough onto a rolling board and roll it out. Cut doughnut shape using doughnut cutter or a cup and a small bottle cap. Take the scraps and roll it again and repeat the same, do this till the entire batch of dough is used up.
Heat oil for deep frying. Drop doughnuts in and fry till golden on both sides.
Remove it to a plate and set aside.
Make glaze by mixing all the ingredients to a little semi thick consistency. Dip doughnuts in and coat on both sides. Arrange it in a cooling rack so the glaze sets and harden.