Step 1In a mixing bowl, mix the salt with the flour. In a separate bowl, combine the milk, honey (or agave) and oil. Pour this into the flour mixture and stir with a large spoon until the dough forms a ball and all the flour is absorbed. The dough will be very soft.
Step 2Knead the dough for a few minutes on a well-floured surface, adding more flour as needed until the dough forms a smooth ball and feels soft and supple but not sticky, like modeling clay.
Step 3Heat the oven to just below 300 degrees. Line three baking pans with baking parchment or a silicone baking pad. Divide the dough into three pieces and form each into a ball. Set two of the dough balls aside and roll out the third. Dust the counter with flour and also the top of the dough, pressing it with your hand to flatten it. Use a straight rolling pin (not a tapered pin) to work the dough to a thin oval or rectangle less than one-eighth-inch thick. Every few seconds lift the dough and dust under it with more flour and dust the top as needed to prevent the dough from sticking to the counter or the pin. If the dough resists and shrinks back, let it rest for a few minutes and move on to one of the remaining dough balls. Repeat the rolling process with each piece of dough.
Step 4Combine the egg with one-half cup water to make an egg wash. Brush the top of the dough with egg wash and lightly sprinkle with coarse sea salt. Cut the dough into desired size for crackers with a pizza cutter or with a knife or pastry blade (you can also use a small biscuit cutter). Transfer the crackers to the pans, placing them very close together (they will not rise or spread). Place the pans in the oven (you can bake them all at once or one at a time). Rotate the pans after 8 minutes (if baking multiple pans, switch shelves). After another 8 minutes, rotate again. Bake an additional 6 to 8 minutes until toasted and light golden-brown, 22 to 24 minutes total. If not brown, increase the temperature by 25 degrees and continue baking until the crackers are golden brown and stiff, not flexible. Remove from the oven and leave on the pan until cool and crisp.