Mill your einkorn berries on the fine setting of your grain mill.
In a large bowl, combine the water, sourdough starter, and sugar. Mix well.
Add the flour and salt and mix until combined and no dry bits of flour are left behind. This will be a shaggy dough.
Cover with plastic wrap and let rest for 30 minutes to an hour.
Start a series of stretch and folds. With einkorn, these are much more gentle than with regular flour.
Gently lift up on one corner of the dough and fold it over onto the center of the dough. Turn the bowl a quarter turn and repeat all the way around the bowl.
Cover after folding and let rest for 30 minutes.
Aim to come back every 30 minutes until you have folded the dough 4-6 times.
After the last stretch and fold, cover the bowl and let the dough continue to ferment for an additional 3-6 hours depending on the strength of your starter.
I let mine rise for 3 more hours and put the dough in the fridge until the next day to shape the bagels.
You will know the dough is properly fermented when it feels like it is full of air and is puffy.
Divide the dough into 8 equal pieces on a lightly floured surface.
Roll each piece of dough into a roll shape and press your finger in the center of the dough ball all the way through to make the hole for the bagel.
Repeat this process with all of the dough balls.
Place the bagels on a piece of parchment paper on a baking sheet and cover with a damp tea towel or plastic wrap to rise for 1-2 hours.
Preheat the oven to 425 degrees F.
Meanwhile, bring a large pot of water to a rolling boil and add 1-2 tablespoons of baking soda.
Carefully drop each bagel in the boiling water with a slotted spoon and let boil for 1-2 minutes. I prefer to let mine go for about 30 seconds for a softer bagel.
Place the boiled bagels back on the baking sheet and sprinkle with everything seasoning, poppy seeds, or sesame seeds. Of course, this is optional.
Bake in preheated oven for 23 minutes.
Let the bagels cool on a wire rack before storing.