On saltine crackers, with yellow mustard.
Apparently, "tin fish" is good for you.
But that's not why grandpa ate them.
He ate them because they were cheap and salty.
When the tin was empty, he'd crush a few saltines into the remaining oil, pour in a touch of vinegar, and eat the slurry with a fork.
This is not for the faint of heart.
In my later years, I discovered that sardines pair well with a cold lager. Something American. Maybe one that's been hiding in the back of the fridge since a Fourth of July barbecue a few years ago.