I had to quit eating beef more than 20 years ago. BUT — in the 1980s:
The best filet I've ever had, outside of Louisiana and Paris, was from a butcher in Cap Ha?tien who dry hung it 90 days in ambient conditions until it had a hard green shell that made it look like a very large howitzer round. Inside, the filet was blue/black, no BS marbling of fat like the U.S. hormone-and-water stuffed schlock — and it cooked without tenderizing and cut with a fork.
Second best was from Erika, a butcher on the corner of San Felipe and Mella in PoP, but they're long gone.
Hispaniola has the oldest beef culture in the western hemisphere, most of which has been lost or modified by immigrants and by superior consumer production from the U.S. and Argentina. The U.S. beef lobby used Mad Cow hysteria to blacklist Argentinian beef, so that even today Asadero Argentina in SD must serve the USDA marbled schlock. But I'm sure that, as in the 80s, if you look well, you'll find a good source in the DR, probably run by a Gallego.
Or buy "free range" local (not hit by a car), and if you don't have the patience to dry hang it for 90 days, marinate in papaya (lechosa). But beef is one thing the DR needn't get dissed on.