Food in Portugal

TripAdvisor.com
Yelp.com
http://catavino.net
https://juliedawnfox.com/portuguese-food-you-should-try/

First, I would suggest a food tour, but with little kids, it would be out of the question, since they take 3+ hours.
Second, talk to the locals in Porto and take the Tram as far as it goes West to the fish market and then back-track a couple of blocks to the beach area where you will find numerous fish restuarants that have gills on the street for great, fresh, fish. That's where we found our best dinners, and were we will return when we're back in October.

I think you can eat very well in Portugal, or very badly. Try to step away from the most touristy areas where it is not nearly as good, and can be very expensive. In general, don't eat at a place they have pictures on the menu!
Here are a few of our favourites:
In Porto we ate at O Cacula, it is near the Igreja do Carmo, so uphill from where you are , but you can walk down to go home. There was a family there when we were there.
In Coimbra, our favourite dinner place was Maria Portuguesa, near Se Velha. You will want reservations as very tiny inside, and service not as good if you are outside. There is also the Cafeteria do Museu in the Science museum which has a wonderful view of all Coimbra, stop at least for a drink. Don't need to pay for museum. For coffee there is also the Cafe Santa Cruz which is a cafe in an old church, great atmosphere.
Lisbon: we stayed up near castle, so I'm most familiar with up there. Le Petit Cafe is fabulous, if you go by 8 can get table. I think would be comfortable with kids. Clara's em Castilla ( ? sp) also fabulous, but I'm not sure I would take kids there as very tiny, little more pricy. I've also heard great things about the Time Out Market.
Not sure how to say in Portuguese, but Bon Appetit!

Here's a restaurant in Porto that my kids loved: The Majestic Cafe. The food was really good.
http://www.cafemajestic.com/en/Utilities/Homepage.aspx

The food in Portugal seems to lean heavily towards seafood, but there are other choices. I found the food to be good, at least with the things I ordered. Especially in Lisbon, you'll probably find that when you're walking down a street with lots of restaurants, you'll have to "walk the gauntlet". The waiters will suddenly appear in front of you and start ushering you to a table. I can understand the reasons for that but found it a bit annoying. That wasn't a problem in Porto.

@Ken
"The waiters will suddenly appear in front of you and start ushering you to a table. "
I expect to have some fun with that approach.
"Sim, mas, tenho de verificar com Yelp."

I just spent a week in Lisbon, so I can only speak about that city. Definitely should go to the Time Out market near Cais do Sodre. Lots of choices of interesting food. Also, the restaurant in the Internacional Design Hotel, in the southeast corner of Rossio square was great. Might be a little on the fancy side for the kids, but it wasn't super expensive and the presentation is very whimsical, so the kids might like it. Definitely hit Manteigaria in the Barrio Alto for their pasteis de nata. The best in Lisbon. And yes, your apartment is in a great location. Enjoy!!

We had a wonderful meal at a restaurant on the water just north of Cascais. It seems to be a Portuguese specialty. It was a whole fish cooked encrusted in salt and when brought to the table the salt crust was cracked open and the lovely moist fish was revealed. Can't remember, if I even ever knew, what kind of fish, just know it was delicious.

Piri piri chicken was on offer everywhere ( and is here in Montreal) but we never tried it. Too hot for our Canadian palates.

davebarnes,

After you've used that routine a dozen or more times, it may start to get a bit tiring. I dealt with the problem of pushy waiters by using a quieter parallel street to the ones the restaurants were on. When I got to the cross street that got me closest to the restaurant I wanted, I'd cut over to "restaurant row".

One other point to mention about Lisbon especially (can't remember whether that was also true in Porto). Many of the ATM's I used had the dreaded Direct Currency Conversion (DCC) option, so be sure to watch for that so you don't get nicked for extra fees.

I think you will find that the food in Portugal is excellent. Check out Anthonony Bourdain's videos on Portugal, both Porto and Lisbon. As in any place, it is a good idea to avoid the most touristy areas. What you want, of course, is to find a place that is popular with locals. I have found that the trip advisor website is quite helpful for restaurants in the Lisbon area.
I am particularly fond of sea food, and the Portuguese cooks know what they are doing, but there are many other choices. For kids, a beef or pork sandwich (prego) is a good choice, and also a bitoque (small thin steak with a fried egg and fried potatoes), are popular choices. You can also get grilled chicken (frongo), but for the kids avoid the piri piri seasoning.
Also of note, the Portuguese like children. I have traveled there a number of times with kids, and I think you will find that children are much more welcome than in the U.S. or Britain. There are many small museums in Lisbon that might be of interest to the children, and Lisbon has a good zoo.