I'm thinking of making something like tuna conserva, starting
with fresh tuna. (Most of the recipes I have googled up
start with an oil-packed can of tuna, to make a conserva-like
item to be served right away.)

My thinking it to braise the tuna slowly, with salt, and a tiny amount
of broth and seasonings, in the smallest Le Crueset I have,
until it is medium-done. Then, tamp it down into a flat
compressed shape, pour a layer of oil on top, and place it
covered into the refrigerator for anywhere from one to three days.

Will this work? Any food safety concerns with this?

Thanks

Steve