Mix together 1/2 cup of chimichurri and 1 tablespoon soy sauce or tamari (you don't want the soy sauce in the final sauce, as it would be far too salty and with an aggressive flavor).
Place steamed tempeh on a plate and pour marinade over. Rub into the tempeh and let sit for 1 hour, flipped in between and rubbing marinade into the other side.
Preheat large heavy-bottomed pan over medium-high heat. Pour in olive oil or spray with olive oil spray and add tempeh in a single layer. Let cook about 3-4 minutes, or until lightly browned. Flip and let cook another 3-4 minutes, until other side is lightly browned. Add remaining marinade from the plate to the pan and cook another 3-4 minutes or so, turning occasionally.