Was in Rio for 4 days.. wanted to share quick notes before I forget (trip is now 2 months ago). Wasn't a culinary experience, but some nice memories.
1) Avoid avoid avoid Zuka. Much better options on the same street. Zuka was terribly overpriced. The food had great ingredients, but prepared very poorly. Lemon risotto looked and tasted like sour curd (shocking bad). Breaded shrimp were overbreaded shrimp that could have been made at the olive garden. The bait and switch on wines is appalling -- twice sent bottle back because it was a different year than advertised on the menu. Food was the main event and felt like I paid $200 for nosebleeds at Yankee stadium on a Tuesday night and the other team failed to show up. Can't stress how overhyped this restaurant is! Please avoid.
2) Had a GREAT meal next door at Quadrucci. Warmed up with a drink at a bar (great) and food was great. Great lamp chops. Great risottos (we tried 2, a malbec and an arthichoke). Tapioca cream desert was so good my wife wouldn't let me finish it all (sometimes she lets me take it all down). I wish I went to this restaurant a second time. Oh yes, the mushroom puffs.. I ordered those twice. I'm not a mushroom guy but those mushroom tarts were so mushroomy.. the caprese ones were eh (wife ate those).
3) Had a quick lunch at an italian place called Prima. I had very low expecations, but the food was solid. Was not a fancy italian meal that would knock your socks off. But pasta perfectly cooked in well executed, not too fancy sauces... hit the spot
4) I think I had sorbet a place liked ?Vero?. Please order the lavander pink lemonade on my behalf. Amaaazing.
5) Went to Venga. A popular tapas place it seemed.. huge crowd. Food was disappointing, although the locals seemed to love it. One sausage dish felt like diced hot dog on a toothpick.
6) memory now stretching. We did a buffet on New Years (only think available). Was actually a pretty good experience. It was definitely premium pricing, but I thought it was fun to see all of the different salads, desserts, meats etc. Maybe there is a high-end one somewhere.. but the fun isn't to do it in a high end hotel, but with locals!
7) in St. Theresa we went to Bar do Mineiro. We hired a guide and he took us there for lunch as his go-to spot for Feijoda (spelling?). That stew just isn't my thing.. so I can't opine. What i do know is that we got there a little early and 1 hour later there was a line of 15 people waiting to go in. And my taxi driver was loving his food. My wife is vegetarian and ordered a salad.. that was just lettuce and avocado and heart of palm.. no dressing not good for her. For meat stew this seems like the popular place to go. Its not a place folks say you should go to though, so its a little off the map, which I liked. I forget the name of the 2 other places in St. Theresa we did not go to.. 1 is up a windy hill and fancy restaurant.. folks we spoke to said food sort of average at best so not worth it.. and there was another local-type spot in st. theresa (?sabor?), our taxi told us it was more expensive and not as good. St. Theresa looks like a touristy area anyway to me so many they are all tourist traps.
8) Churro from street vendor. Fantastic.
9) Academy of Cachacha for drinks. Not very fancy for such a fancy name! 1 block away from a super market and sort of divey feeling. But not a bad place to tell your friends you went to. Strong, albeit quite sour, drinks for us.
10) Late night pizza guanabara. Wow. Look at that cheese. Is there even tomato sauce!? Just cheese and bread. And packed late night. hung over was great.
11) Quick bite at a cafe ?now i can't remember? Simple place with great salads and light sandwiches. I got a chicken paillard and the chicken tasted like real chicken (not purdue)
I hope this helps. Spent vast majority of our time in Leblon/Ipanema. Don't see why would spend any time anywhere else really. Not sure if Rio is the city for us.