Whisk 2/3 cup warm water and 1 teaspoon dry yeast together until yeast is dissolved. Add einkorn flour and mix with a spoon until no dry spots remain.

Cover and leave at room temperature for 4-5 hours.

At the end of that time, when the starter dough is very bubbly and wet, add 1.5 cups warm water and whisk until the dough is dissolved.

Add 4 cups all-purpose einkorn flour and 1 teaspoon sea salt. Mix with a spoon until you get sticky dough. Leave covered for 30-60 minutes.

Line a cookie sheet with a double layer of parchment paper.

Sprinkle the dough generously with water, wet your hands and knead for a couple of minutes, wetting your hands often to prevent stickiness.

Sprinkle the parchment paper with water, transfer the dough, and shape it into a ciabatta-like shape. Spray or sprinkle the top generously with water and cover with plastic. Leave to rise for 2-3 hours, or until it more than doubles in size.

Preheat the oven to 400ºF (200ºC). Remove plastic cover. Bake for 30-35 minutes, or until the top starts to turn slightly golden. Do not over bake, otherwise it'll become too crumbly.