Title says it, really. I remember my uncle (the French) saying it on just about every meal, but I cannot remember what it was. It was a single word to mean mopping up the sauce from the plate using a piece of bread. Anyone? Quelqu’un?
The French verb for cleaning sauce off the plate with a piece of bread is “saucer” (sounding more or less like “so-say” in English).
Your uncle might have said “sauçons!” (“let us saucer!”) or something like that. Or he might have used a different word entirely, for all I know; family sayings can be pretty idiosyncratic.
Why can’t we have fun and useful verbs like that in English. Heck , I don’t think we even have that in Spanish.
I seem to remember a long word, but if there is a standard verb for just that action, I don’t think we would say something else.
He could also have (mis)used the word “chabrot” or “chabrol”, which means diluting what’s left of one’s soup/sauce in the plate at the end of a meal with half a glass of wine , then drinking the mix or *saucing *it with bread.
It’s very old fashioned though - far as I remember, I don’t think I’ve ever seen anyone “faire chabrot”. I guess the custom appeared back when wasting any bit of food and drink was a big no, and was phased out in our times of plenty.
I don’t think it was that but “faire chabrot” is now definitely on my list of things to try.
rebañar
My country dad calls it “soppin’ bread”, nounwise anyway.
Isn’t that when you have a lot of sheep and you cut them in slices?
In any case, it would be when you have a lot of sheep in individual pens and group them up 
(for those scratching their heads: rebaño means flock)
and “rebanar” (With n not ñ) means slice.
like lamp chops?
Be sure the lamp is unplugged before you fillet it, though!
I would have thought rebañar would mean “to bathe again” 
time to clean my glasses and stop relying on the spell check to show a big red warning. ain’t none no typist either.
Mine too! Dammit this kitchen renovation is taking too long.
Dunno about French, but in English the word is “sop.”