To Make the Horns:
1.Mix flour and salt in large bowl.
2.Make a well in the center and pour in the lemon juice and water.
3.Mix flour and water with fingertips to make a soft dough.
4.Form dough into a ball, cover completely with plastic wrap, and refrigerate for 20 minutes.
5.Lightly flour the butter and place between two sheets of wax paper, set aside.
6.After chilled, remove dough from refrigerator and place on lightly floured smooth surface.
7.Roll out dough leaving the center a little bit thicker.
8.Remove wax paper from butter and place the butter in the center of the dough.
9.Fold dough around butter on all sides, like an envelope.
10.Roll out dough into a rectangle, about 18 inches.
11.Fold the dough in thirds, like a letter.
12.Turn dough one quarter turn and roll out into a rectangle, about 18 inches.
13.Fold the dough in thirds, like a letter.
14.Wrap the dough in plastic wrap and refrigerate for 40 minutes.
15.Repeat steps 10-14 two more times.
16.Roll out dough into a 10 by 15 inch rectangle about 1/8 inch thick.
17.Cut dough lengthwise into 1 inch wide strips using a pizza or pastry wheel.
18.Grease cones with unsalted butter.
19.Wrap each strip of dough around the cone, starting at the bottom and overlapping slightly all the way to the top.
20.Pinch the bottom and top to make sure the dough doesn’t come unraveled.
21.Place horns, sealed side down, on a baking sheet and refrigerate for 30 minutes. (At this point, you can freeze the horns for later baking or continue with the baking in the next steps.)
22.Preheat oven to 400 degrees.
23.Whisk the egg and tablespoon of water together in a small bowl, set aside.
24.Remove horns from the refrigerator.
25.Brush horns with the egg wash.
26.Sprinkle sugar crystals over the top of the horns.
27.Bake about 15 minutes, or until golden brown.
28.Remove from oven and transfer to cooling rack, leaving cones in for 10 minutes.
29.Remove cones from horns and let cool completely.