I am the biggest fan of Asian food and I have lived in Lisbon for over 8 years and tried almost all Asian restaurants...and here are my go-to spots that never fail to satisfy my Asian food cravings.
From delicate dim sums at Macau Dim Sum, to the very spicy Sichuan style cuisines, there are numerous authentic Chinese restaurants in Lisbon. For the mid price range, my go-to places are Chuanyue and Nova Paris. If you crave hot pot, Sweet Olive is the right choice. If you are looking for something fancier, try the Old House. As for the affordable and authentic options, Kuwazi, Dawanmian, and Pangzi are among the best.
There are countless of Japanese restaurants in Lisbon. Diners can max out their credit cards with luxe omakases at Kanasawa (an above €100-per-person sushi counter), or find quality and umami-rich fish at more affordable prices (a $29 lunch set at Lisbon Sushi Club is among the best). Vegans need to try Legumi Sushi. Some of my favorites include SushiCafe Avenida, Go Juu, Yakuza by Oliver, Nomada, Aron Sushi, and Tasca Kome.
The most fun and luxury mention is JNCQOI Asia. You will also have a good time at Boa Bao in Chiado if you don't mind fighting over a table with floods of tourists.