Dump the chickpeas into a medium mixing bowl, cover them with warm water and stir in the baking soda. Allow them to soak at least 8 and up to 12 hours. Drain them and rinse them well.
Throw the soaked chickpeas into a large pot, cover them with water by two inches and bring them to a boil over medium high heat, boiling them until tender.
Heat the oven to 350F, and then grease and flour a 9-inch tube pan.
Drain the chickpeas, and place them in a high-powered blender (This is the one we use.) Add the olive oil, tahini, salt, eggs, honey and arrowroot powder to the blender. Grate the rind of two lemons very finely, and add it to the blender. Juice the lemons and add the juice to the blender. Blend all the ingredients together until they form a smooth, uniform batter.
Bake the cake at 350 F for 1 hour, or until a toothpick stuck into the middle of the cake comes out clean. Allow the cake to cool, in its mold, on a wire wrack for 15 minutes. Carefully unmold the cake onto a platter, and serve it warm.