Mix the ingredients in a large bowl. Cover and let soak for at least 30 minutes. You can also let the batter ferment for several hours. If the ambient temperature is warm, limit the fermentation to six hours to prevent too much sour flavor and make sure your bowl has room for doubling.

Preheat the oven to 325°F, set up a shelf in the middle and one higher in your oven, and line two baking sheets with parchment paper.

Dump half the batter onto one of the lined baking sheets. Using an offset spatula, spread the batter as evenly as possible, ⅛ - ¼ inches thick.

Repeat with the second baking sheet and the rest of the batter.

Put both sheets in the oven and bake for 10 minutes. Remove from the oven and cut the partly cooked batter into a grid. I used a pizza wheel.

Return the baking sheets to the oven and bake for 50 minutes more. Swap the upper and lower position of the sheets partway through the bake, and rotate them 180° also if needed to bake evenly.

When the crisps are dried out and have hints of gold color, they're done baking. Don't let the crisps brown as this imparts a burnt flavor.

Remove from oven, break the crisps along the cut lines, and cool on a rack.

Store in a closed container. If you find the crisps get soft e.g. if you live somewhere humid, re-crisp the entire batch on a baking sheet at 180°F for an hour, then crack the oven while they cool down for several hours before storing again.