Vegetarian/vegan recommendations Porto and Lisbon

One thing I remember from Portugal was that most of their vegetables are eaten as soups.

Happy Cow has been around forever: https://www.happycow.net/europe/portugal/
One thing I always find helpful is to check out cookbooks and look for specific dishes so you know what to look for in any restaurant (my perception is it's slim pickings, so I hope to be disabused of that notion!).
If you google "vegetarian portuguese dishes," you'll get some informative results--this one has the pertinent phrases you'll need: https://www.practiceportuguese.com/being-a-vegetarian-in-portugal/

We are vegetarians and enjoyed many absolutely delicious meals when we were in Porto last month. Overall, we found it pretty easy to find places that we wanted to eat at, because many restaurants had vegetarian and even vegan dishes that they put a lot of thought and care into. Lots of places had their own homemade, wonderfully spiced veggie burgers, for example.

Here are some of our favorite places that we went to:

Callejero Tacos had some of the best Mexican food that I have ever had in my life. While most of their items have meat in them, they have some incredible vegan and vegetarian dishes as well, such as the cactus burrito and the unforgettable guacamole. https://www.instagram.com/callejero.tacos

Garden Porto has many vegan and vegetarian options and everything that we had was terrific. I especially enjoyed the Eggs Florentine. https://gardenporto.eatbu.com

Porto dos Gatos is a vegan restaurant that is also a cat cafe! We had amazing veggie burgers and an incredibly decadent piece of chocolate cake there. They have a wonderful outside seating area at the back of the cafe where the kitties hang out. https://www.instagram.com/oportodosgatoscatcafe

Da Terra is a vegan restaurant where the food is served buffet style. Everything that we had was so fresh, colorful and really tasty. https://www.daterra.pt

BUGO Art Burgers had a few different veggie burgers on their menu. The chickpea burger was scrumptious, as were the homemade chips. https://bugoartburgers.eatbu.com

We also really wanted to go to The Bird, but they were closed the day that we tried to go there, unfortunately. Their patio looked really inviting. https://m.facebook.com/theBird.pt

I hope that this helps! Enjoy your trip!

Thanks for suggestions!

In Porto:

Da Terra, Rua Mouzinho da Silveira

Em Carne Viva, Rua da Boavista

Both very good.

Almost all restaurants have a vegetarian dish, the problem is that they think, salmon for instance, is a vegetal. They assume vegetarians don't eat meat, so they serve all kind of dishes with eggs, cheese, etc.

Another thing is that sometimes restaurants forget that vegetarians eat hydrates. So they serve you, for instance, an excelent curry of mushrooms, peanuts and celery but... where is the rice?

Those I mentioned above are really good, and the real thing.