Mix the Dough: In a large mixing bowl or stand mixer, combine the sourdough starter, warm water, bread flour, sugar, salt, and barley malt syrup. Mix until a shaggy dough forms.

Knead the Dough: Knead the dough for 8-10 minutes until smooth and elastic. If using a stand mixer, knead with the dough hook on medium speed.

First Rise: Cover the bowl with plastic wrap or a damp towel and let the dough rise at room temperature for 4-6 hours, or until doubled in size.

Shape the Bagels: Punch down the dough and divide it into 8 equal pieces. Shape each piece into a ball, poke a hole in the center with your thumb, and gently stretch to form a bagel shape.

Second Rise: Place the shaped bagels on a parchment-lined baking sheet, cover, and let rest for 1-2 hours, or refrigerate overnight for a slower rise.

Boil the Bagels: Preheat your oven to 425°F (220°C). Bring a large pot of water to a boil and add the baking soda. Boil each bagel for 1 minute per side, then remove with a slotted spoon and return to the baking sheet.

Bake the Bagels: Brush each boiled bagel with beaten egg and sprinkle with your choice of toppings. Bake for 20-25 minutes or until golden brown.

Cool and Serve: Allow the bagels to cool slightly before serving warm or at room temperature.