In a mixing bowl, combine warm water and active sourdough starter.

Stir in bread flour, sugar, and salt until a shaggy dough forms.

Transfer the dough onto a floured surface and knead for about 5-7 minutes.

Place the dough in a lightly greased bowl and cover it with a damp cloth. Let it rise at room temperature for about 1 hour or until doubled in size.

Once risen, punch down the dough and divide it into 8 equal pieces. Form each piece into a ball and poke a hole in the center.

Bring a large pot of water to a boil and add baking soda. Boil each bagel for about 1 minute on each side.

Preheat your oven to 425°F (220°C).

Transfer the boiled bagels to a baking sheet lined with parchment paper. Brush with the beaten egg and bake for 20 minutes until golden brown.