re: Croatia

Plenty of good food. Though funny enough, most of the widely regarded restaurants are in Istria near Italy and are Italian restaurants.

For Dubrovnik we ate at Restaurant 360, Nautika, Arsenal, Restaurant Panorama (these names aren't very creative ) and at our hotel.

I'd recommend Restaurant 360 (request to sit on the wall), Nautika (obviously first row on the patio), and our hotel (Hotel Excelsior Dubrovnik). Panorama is fine for the view, but I ate lunch there. Same for Arsenal, can't give it a fair review. Taj Mahal (again with the names) is supposedly good Bosnian food, not Indian but we ran out of juice as my wife was pregnant.

5 days is a lot for Dubrovnik IMO, but in your case it's not really five days.

If you end up adding time to Split I can recommend some restaurants there. If you want to get really far about on your transfer from Dubrovnik to Split and don't care how long it takes there's the Blue Cave near Vis Island and a beach there called Stiniva for the Instagram, but that's considered far. However, you said "can't miss" so I'm throwing the sink at you. I didn't make it to all these places but I do a lot of research on places I go.