S.O.S. (Salmon on a Shingle)

I spent about a year making breakfasts at a local homeless shelter once a week. I would wake up around 4:00 a.m. and cook for anywhere from fifty to one hundred people. I had a few popular dishes that people seemed to like, but one that always received good reviews was some version of S.O.S. (slop–or a different four-letter word–on a shingle), which is some sort of gravy on toast. It’s filling and cheap to make. You can use almost any leftover meat in the cream sauce, but salmon is a partic