In the refrigerator I have a small, organic, rib eye wet aging...for lack of a better term. There is no visible marbling on this steak. I was thinking to cook low temperature sous vide, then sautee in butter.
Any other suggestions.
A rib-eye without marbling suggests that the cow was finished on grass, and not for a very long time. No idea about breed ... I think the way cattle are raised and fed has a bigger impact than the breed. I buy Piedmontese beef from time to time. Some of it is grain finished and rated prime ... lots of marbling. Some is grass finished and has less. Interestingly, it's possible to finish on grass and get a lot of marbling, but only some farmers go through the trouble. Some also finish on a mix ... raise them in a pasture, but put out grain for them to snack on. Contrary to what grass-feeding activists will tell you, the cows run to the grain.
Really lean beef is indeed tricky to cook. I haven't tried it sous-vide. Since you don't have to melt the marbling, you can try temperatures lower than medium-rare. But I don't know what will give the best mix of tenderness / juiciness / flavor. My starting point would be to try cooking in a 55°C bath to an internal temp of 54° or 53.5, and not leave it in for a minute longer than necessary. Then brown in a pan with oil, so you can get a more even crust without burning anything.
In general, I think 1.5" is the ideal thickness for sous-vide steaks. I'd rather get one steak to share between two or three people than to try to cook individual ones that are too-thin. 1.5" is thick enough that you can easily sear without worrying about overcooking the middle, but thin enough that s.v. times are reasonable.