I can't claim any credit here. David Lebovitz, an American chef living in Paris hosts an excellent site (try his tarte au citron) provides the recipe.
I used Doves Farm Buckwheat flour. Buckwheat is actually made from the seed of buckwheat plant, a close relative of Rhubarb. And from Doves Farm:
"The specific characteristics of buckwheat proteins, and the relative proportions of its amino acids, make buckwheat the unsurpassed cholesterol-lowering food studied to date.Compared with true grains, buckwheat is high in minerals: especially zinc, copper, and manganese.Healthier fat profile. Unlike true grains, buckwheat’s low fat content is skewed toward monounsaturated fatty acids—the type that makes olive oil so heart-healthful."