This unusual (but I think delicious) recipe is purported to originate in the vanilla-producing regions of eastern Mexico. It calls for the use of pure vanilla extract; artificially flavored vanilla extract would be a poor substitute for the real thing. It is very peppery, which we like, but if you want less heat I would begin by cutting the pepper called for in half. Serve over lots of rice, this makes a lovely sauce! Prep time DOES NOT include minimum 1 1/2 hr marinating time, so plan ahead.