Anju Noodle Bar (lunch and dinner, just across the river in Kittery) remains an area favorite. We usually make a meal out of whatever appetizers appeal that day, with the cauliflower as a must-order.
I haven’t spent much time in Portsmouth proper recently but I do remember good dinners from Moxy’s (creative regional and seasonal tapas-style plates, on my list for a re-visit) and Black Trumpet (their adjacent Stock & Spice shop was also good).
Portsmouth is a great town for walking around and exploring. Looking forward to hearing about what you find!