What could be more magical than making a rainbow? We’ve chosen rainbow hues for this dough, but feel free to experiment with your own favourite colours to make the bagels your own.
Place the flour in a mixing bowl, add the yeast to one side and the sugar and salt to the other. Add three-quarters of the water and turn the mixture with your fingers. Add the remaining water, a little at a time, until all the flour is incorporated and you have a rough dough.
Tip the dough onto a lightly floured work surface and knead for 5–10 minutes, to a soft, smooth ball.
Divide the dough into 5 equal pieces and cover with a damp tea towel. Working with 1 piece of dough at a time, turn each into a different colour. Add 3 pea-sized drops of food colouring onto the dough, then fold it up and around the colouring. Knead to an even colour, adding more food colouring, a drop at a time, until bright. Place the coloured dough into a greased bowl.
Repeat with the other 4 pieces of dough until you have 5 brightly coloured portions of dough. Cover each bowl with a tea towel and leave to rise for about 45 minutes–1 hour, until doubled in size.
Turn out the red dough onto a lightly floured work surface and, using a rolling pin, roll out to a 20 x 12cm rectangle. Set aside. Turn out the orange dough onto a lightly floured work surface and roll out also to a 20 x 12cm rectangle. Place the orange rectangle of dough neatly on top of the red.
Repeat with the yellow, green and blue doughs, rolling each one out and placing on top of one another, until you have a stack of 5 layers of dough, red at the bottom, then orange, yellow, green and blue.
Cut the stacked dough into six 20 x 2cm-wide slices, slicing down through the layers, so each strip has 5 layers of colour.
To shape the bagels, lay one of the stacked dough strips on your work surface and place the palm of your hands at each end. Simultaneously, gently move your right hand forwards and your left hand backwards to twist the dough into a rope about 26cm long. Pinch the ends together to form a circle and gently roll the join backwards and forwards to seal. Repeat with all the strips.
Place the bagels on the lined baking sheets, then place in proving bags and leave to prove for 20 minutes, until risen and puffed up.
Heat the oven to 200°C/180°C fan/400°F/Gas 6.
Bring a large saucepan of water to the boil. Add the bicarbonate of soda (this helps to form the shine and chewy texture of the crust).
Plunge the bagels, 2 or 3 at a time depending on the size of your pan, into the boiling water. Cook for 30 seconds on each side, until the bagels puff up and the shape sets. Using a slotted spoon, remove each bagel from the water and transfer back to the baking sheet.
Bake the bagels for 25–30 minutes, until cooked through. Remove from the oven and transfer to a wire rack to cool.