Sift the flour and baking soda onto a sheet of waxed paper; set aside.
In a 1 1/2-quart saucepan over low heat, combine the butter, sugar, cinnamon, and water. Stir occasionally just until the butter melts. Do not allow the mixture to boil. David Lebovitz recommends not letting the sugar melt thoroughly—the crunchy bits make for wonderful texture in the cookie. Remove from heat and stir in the almonds. Pour this mixture into a 3-quart mixing bowl; set aside for about 30 minutes at room temperature until lukewarm, about 90° F.
Add the dry ingredients all at once; stir thoroughly until blended.
Press the soft dough into an 8 1/2- x 4 1/2-inch pan, preferably straight-sided (such as a 1 1/2-quart Pyrex loaf pan) lined with plastic wrap. Cover surface with plastic wrap and refrigerate or freeze until firm.
Adjust rack to lower third of oven and preheat oven to 325° F. Line two large cool baking sheets with parchment paper.
Lift out the firm dough from the pan onto a cutting board. For larger cookies, simply slice as thinly as you can, crosswise. For smaller cookies, cut dough in half crosswise and then cut the halves lengthwise into thirds. Using a sharp knife, cut each bar into 1/8-inch or thinner slices, and space them 1/4 inch apart on the baking sheets. (The dough slices as though it were fudge.) You can use a sawing action with a serrated knife in order to cut through the nuts to make very thin slices.
Bake, one sheet at a time, for 8 to 10 minutes, or until the undersides are light golden; then turn cookies over and bake for an additional 8 to 10 minutes, or until crisp and honey-colored. Place baking sheet on a wire rack to cool. Lift cookies from parchment when cool.
Stack cookies in an airtight container and store at room temperature up to 10 days.
Note: Hawaiian washed raw sugar is available in supermarkets in 2-pound plastic bags. If you cannot locate it, you can substitute turbinado or Demerara.