Add starter, water and sugar to a large bowl and whisk together.

Add the flour and salt and combine (using hands and/or dough scraper). This doesn't need to be perfect but you're aiming for all the flour to be incorporated in to the dough. Cover with a damp tea towel and leave to rest for 30 minutes.

After the dough has rested, quickly work it into a smooth-ish ball and place in a lightly oiled bowl. Cover with the damp tea towel and leave to rest until the dough doubles in size, 8-10 hours (or overnight).

Line baking tray (I needed 2) with parchment paper and oil lightly. Remove dough onto non floured surface and separate in to 8 balls. Place the balls on the baking tray and cover again with the tea towel to rest for 20 mins.

Once rested, pick up each ball and form a hole in the middle using your thumbs while gradually rolling the dough to form a bagel shape. Place back on the baking tray for another 20 mins. Whisk together the agave and water in a pan and bring to the boil. Preheat oven to 220°C.