Combine flour, salt and cold butter cubes in the bowl of a food processor. Pulse several times until cubes are the size of a pea. Add ½ cup ice-cold water and pulse 3–4 more times.

Transfer mixture to a large bowl. Squeeze into a ball until dough is moist but not sticky. You can add a couple more drops of water if it is really not coming together, but remember that it takes time for einkorn to absorb fat and liquid. So if it is close, you’re there. Cover the bowl and let it rest for 30 minutes.

Bring the bowl back to your work surface and form pie dough into a single ball. Chill in the fridge at least 45 minutes.

Once dough has chilled, preheat oven to 425 degrees and line a baking sheet with parchment paper.

Remove dough from the fridge and place on a floured work surface. Roll the crust into a circle 14"–16" in diameter, dusting with flour as needed to prevent sticking. Then, roll the dough around the rolling pin and transfer to the baking sheet. Einkorn pie dough is delicate, but mends easily by pinching any tears together with your fingers.

Toss the peaches, sugar, lime juice, cornstarch and salt in a large bowl until the cornstarch is completely dissolved. Spoon the filling into the center of the crust, leaving a 2" border all the way around. Fold the crust over the filling then brush some egg wash under any dough that overlaps—it’ll help the folds stick to one another. Dot the top of the filling with butter then brush the entire surface of the crust with the remaining egg wash. Dust with cinnamon.

Bake 20 minutes then rotate the pan and bake an additional 20–25 minutes. When the crust is golden brown and the center is piping hot and bubbly, remove the tart from the oven.

Stir the apricot jelly and hot water together to create a glaze then brush over the filling. Allow the tart to cool just long enough for the filling to set. Cut into wedges and serve warm.