The last time I was in Mexico I was going slower than usual through the market. With both Ruth Alegria and my pal Yunuen at my side, I asked about everything I saw that I didn't know. 

A bag of grey dust looked intriguing.

It turns out to be Tequesquite.

Unless I misunderstood, it's dried lake scum from Lake Texcoco. Chemically, it's similar to bicarbonate of soda. For centuries, it's been used to soften old beans and as a leavening for tamales.

I've used a very small amount in my beans and I can't seem to tell anything much one way or the other. I have heard of people putting baking soda into their beans to soften them but I have to confess this sounds very unappealling. Somehow in my mind, dried lake scum makes more culinary sense.

I think most people would nod their heads and mention how darn interesting that was but I of course thought about how much I could bring back into the states and then my mind raced even further and I wondered about importing it to sell on the Rancho Gordo website. Let's just say I'm working on it!