There are dishes that cause me to lose all self-restraint. This rich, silky chicken liver mousse from Chef Aaron Barnett of the charming Lyon-style bistro St. Jack in southeast Portland is one of those dishes. I embarrass myself (and my husband) with moans of delight every time I order this version of the French classic. Chef Barnett serves his mousse with slices of crusty baguette, but the Perfect Cro