Sweet Black Beans

Ingredients:
1 cup dried kuro mamé, 3 cups water for soaking and cooking beans, 1 teaspoon baking soda, 2 cups sugar, 1 1/2 cups cold water for syrup, 2 teaspoons soy sauce

Instructions:
Rinse the dried beans. In a deep bowl, mix the 3 cups water and baking soda, stirring to dissolve the baking soda. Add the beans and let them soak, completely submerged, at room temperature for at least 8 hours or preferably 10 to 12 hours (if it is very warm in your kitchen, soak the beans in the refrigerator for 24 hours). As the beans soak, they will swell to several times their original size. To make sure they remain moist throughout the soaking, dampen sarashi or several layers of finely woven gauze or cheesecloth and place directly on the soaking beans.
Transfer the swollen beans and what remains of their soaking water to a deep 3-quart pot. If the beans are no longer covered with water, add water as needed to cover them. Place over medium-high heat and bring to a boil. Skim away any aku (froth, scum, or film) with a fine-mesh skimmer and add water as needed to cover the beans by about 1 inch. Adjust the heat to maintain a steady, not-too-vigorous simmer. Place the cloth you used when soaking the beans on top of the simmering beans. The cloth will become discolored, but if it is sarashi or other sturdy muslinlike cloth, it can be reused for the same purpose several times. If you have an otoshi-buta or other flat lid slightly smaller in diameter than the rim of the pot, place it on top of the cloth.
Cook the beans for 2 hours, checking the intensity of the heat and the water level every 15 to 20 minutes. Ideally, the beans will gently simmer in water that barely covers them. Throughout, keep the surface of the beans moist with the cloth (and otoshi-buta).
As the beans cook, some skins may loosen and a few beans may split, but neither is a good indication of tenderness. To check for tenderness, take a bean from the pot, and when cool enough to handle comfortably, hold it between your thumb and pinkie and press gently. It should yield easily. (This pinch test is accurate because the pinkie is usually a "weak" finger and can exert less pressure in the pinch. If a simmered bean can yield to this weaker pressure, you can be sure it is tender.) Cooking times will vary tremendously with the age and variety of the soybean. On some occasions, I have had to cook beans for 4 or more hours. Continue to cook the beans, checking the water level frequently and adding water as needed to keep the beans barely covered, until they are completely tender. At this point, the beans and their cooking liquid can be immediately transferred to a glass jar, covered with the cloth, then with a tight-fitting lid, and refrigerated for up to 3 days. (Before closing the jar, make sure none of the beans is exposed to air.)
Make the syrup: Combine the sugar and 1 1/2 cups water in a deep, heavy 2-quart saucepan over medium heat, stirring to dissolve the sugar. Reduce the heat slightly and continue to cook, stirring occasionally, until the liquid is syrupy and reduced to about 1 cup. This should take about 10 minutes. During this reduction process the bubbles will become quite frothy.
When ready to combine the syrup and beans, remove the otoshi-buta and cloth from the beans in the saucepan or open the jar and peel back the cloth and transfer to a heavy pot. Add the syrup, replace the cloth, and bring to a simmer over medium heat. Simmer for 10 minutes, or until the beans are barely covered with the syrup.
Remove from the heat and allow the beans to cool to room temperature in the syrup. During the cooling process, the sweetness of the syrup penetrates to the core of the beans. Make sure the beans are covered with the cloth as they cool to avoid excessive wrinkling of their skins.
Peel back the cloth, add the soy sauce to the cooled syrup (it will mellow the intense sweetness), and stir to distribute well. Replace the cloth and place the pot over low heat. Bring the syrup slowly to a boil and cook for 2 minutes, then remove the pot from the heat. Allow the cloth-covered beans and syrup to cool to room temperature again. It is in this final cooling process that the flavors develop and meld.
Set the beans aside to cool completely, then transfer them with their syrup to a clean glass jar. Seal with a tight-fitting lid and refrigerate for up to 10 days. If you wish to store the beans for an extended time, use heatproof canning jars and process in a boiling-water bath as you would a jam or jelly, then store the cooled jars in the refrigerator for up to 2 months.