In a large mixing bowl, combine the active sourdough starter, warm water, and sugar. Mix until the sugar dissolves.

Gradually add the bread flour and salt to the mixture, stirring with a wooden spoon or dough scraper until a shaggy dough forms.

Turn the dough onto a lightly floured surface and knead it for about 10 minutes until smooth and elastic.

Place the kneaded dough back in the bowl, cover with plastic wrap, and let it rise at room temperature for about 2-3 hours, or until doubled in size.

Once the dough is ready, punch it down to release the gases and divide it into 8 equal pieces (about 100g each).

Roll each piece into a ball, then poke a hole through the center with your thumb. Stretch the hole to create a bagel shape. Place the shaped bagels on a baking sheet lined with parchment paper.

Cover the bagels with plastic wrap and let them rest for about 30 minutes, allowing them to puff up slightly.

Preheat your oven to 220°C (425°F).

In a large pot, bring water to a boil and add the baking soda.

Carefully add the bagels to the boiling water, a few at a time. Boil each bagel for about 30 seconds on each side to achieve a chewy texture.

Use a slotted spoon to remove the bagels and place them back on the parchment-lined baking sheet.

If desired, sprinkle the tops of the bagels with optional toppings like sesame seeds or everything bagel seasoning.

Bake the bagels in the preheated oven for about 20 minutes, or until they are golden brown.

Remove from the oven and allow them to cool on a wire rack before serving.