Went to NZ for 3 weeks in Dec 2018. A few places were memorable for good reasons, others less so. You can get updated reviews on Yelp or other such places, but this is Chicago so we LTH it! Most places are locally owned (not a ton of chains). Also see a note on NZ food and groceries in general, below.
Best restaurants we visited: (in the order we traveled)
Amisfield Bistro, Queenstown – Outstanding prix-fixe meal with wine pairings. Try the 2015 Pinot Noir...their best offering. Unfortunately not available in the US. The 2016 is, but it's merely good while the 2015 is GREAT. This is one of the best restaurants in the country, though, so if you can book weeks in advance you’re much more likely to get a table.
Fergburger, Queenstown. Pick a burger, any burger. Advise going during off-peak times to avoid the lines. We had a late lunch at 3 pm and had a 15 minute wait. It was totally worth it.
Fergbaker, Queenstown. Like the burger shop but with baked goods. Usually no more than a 10 minute wait, if that. Very, very good.
The GYC - Glenorchy Cafe and Bar, Glenorchy. We were advised by locals that this was the best place in town to grab lunch. Enormous and very good open-faced sandwiches! If you tour the Dart River or want to see Isengard or where Boromir met his end, this is a good place to have lunch.
Fat Pipi Pizza, Hokitika – Very good pizza and salads, just off the beach. Be brave and get the whitebait pizza! Surprisingly not fishy at all and quite nice.
Stella Café, Hokitika—Outstanding breakfast spot. Can't go wrong here.
The Store, north of Clarence (just off SH1 between Blenheim and Kaikoura). Do. Not. Miss. This. Place. Simple yet outstanding sandwiches, baked goods, coffee, etc. You won’t be sorry.
Kaikoura Seafood BBQ Kiosk, Kaikoura—very fresh lobster (often referred to by some locals as "crayfish") and other seafood cooked to order in a quaint roadside location. Be prepared to spend some $$$ here as it is not cheap, but it was very enjoyable.
Twenty Seven Steps, Christchurch—second best meal we had in NZ (after Amisfield Bistro) at about half the cost. Lovely setting, outstanding service. We’ll go back next time we’re in town.
Black Betty Café, Christchurch—the best breakfast we had, and they take their coffee very seriously here. Worth a visit if you are in Christchurch.
Decent places, worth considering:
Sugar Loaf Cafe, Glenorchy...we had only had coffee and baked goods there, and these were good. They are open early in the morning.
The Coffee Club, High Street, Auckland. Surprisingly good salads for not a lot of money. Good budget stop.
WGK - Wanaka Gourmet Kitchen, Wanaka. We split a lamb shoulder here, and it was good if not great.
The Doughbin, Wanaka. Signs in the window boast of award-winning meat pies. Ours were OK. Not sure if they had been sitting for a while before we bought them, or of they had an off day, but if this was not the case, the bar for meat pies in NZ is not very high.
SnakeBite Brewery, Franz Joseph Glacier. Good local beer. We had some stews that were interesting, if not super-memorable. Not many places to eat here, and what there is seems to be angling for the tourist dollar.
Lombardi’s, Nelson. Had the advantage of being open for dinner on Christmas Eve and not booked up with reservations. OK if not remarkable food.
Disappointing:
Hans Herzog Restaurant, Marlborough. Very overpriced and very underwhelming prix fixe menu. Our experience at Amisfield (see above) was much, much more enjoyable for about 2/3 of the cost. Also, they didn’t tell us there was a surcharge for dining on Boxing Day until we were paying our bill, which didn't seem fair.
Gipsy Moth, Auckland Int'l Airport Domestic Terminal. We found the food to be very basic, very average, and very expensive.
A note on NZ restaurants and groceries: Food in general is much more expensive in NZ than in the US, and most Kiwis do not eat out nearly as often as we are used to doing in the US. Meat pie stands are ubiquitous, and the quality is highly uneven.
We did AirB&B quite a bit and were able to prepare meals for ourselves to help hold down costs. Of the NZ grocery chains, New World and Four Square are the priciest, with Countdown somewhere in the middle, and Pak-N-Save as the budget end. We only bought wine at a Fresh Choice but my impression is that it’s not as nice any of the others. We stuck with Pak-N-Save and New World due to their high quality. We missed farmer’s markets due to our travel schedule, but would make it a priority to visit them when we return.
NZ groceries can be amazingly fresh. Eggs with tall, bright orange yolks looked and tasted as if they were just off the farm, and the greens we had in restaurant salads tasted like they had just been picked.
One final observation: doughnuts are not a phenomenon in NZ. Aside from the Dunkin’ Donuts at the Auckland airport, we saw only one place in Nelson that advertised doughnuts, and it was out of business. So either there is a huge opportunity here or NZ is where doughnut purveyors go to fail.