What cut of beef might this have been?

[chocolatetartguy]

It was an ingredient in a beef and vegetables dish at a Vietnamese restaurant. The beef was in 1x3" wide slices and had a lot of marbling. It was tender and reasonably flavorful and had a rim of meat above the fat streaks. I would say that they usually use flank steak in their beef stir fries, but this wasn't flank. Mighten this have been the last of a cut of beef that normally goes with pho? I should have asked and now they will be closed for a month.

[Brandon Nelson]

You don't have much to go on. If i were to guess I would say it was hanger or sirloin flap. Both of these cuts are cheap enough to find their way into the dish you describe. Both are also tender and tasty. Flap meat is cut into skirt steaks, arrachara, and carne asada.

[Karl S]

Flap meat is not skirt. Skirt is a very specific cut.

[Brandon Nelson]

Flap meat is a sirloin sub primal. Trimming this sub primal and then cutting it on a long bias into butterflies (how it is done on Central America) or wafers (more European) yields skirt steak.

I have cut more than a few of them.

[Nanzi]

Skirt steak? That is used in many Asian dishes.

[Violatp]

Boneless short rib, maybe?

[Karl S]

Either that or brisket or navel/plate (the area where the best pastrami is made from; the kind with lots of streaks of fat).