Thanks for stopping by to read mmm-yoso!!!, a food blog. Cathy is writing today. Kirk and His Missus are having a wonderful time on vacation.
I've written about Oishii three times, the latest was in 2011. Back then, it was only one of two Thai restaurants in Santee and the two sided menu had more Japanese choices than Thai. Now Santee has five Thai restaurants. Anyhow, at some point during the Covid-19 slowdown, the "Japanese" menu/Oishii/sushi bar disappeared and Thai Thai (there's another location in Fallbrook) became the name of the restaurant with the menu being only Thai. A few months ago, the original sushi chef, Mike, returned and so did the sushi bar and the name.
The interior had undergone changes.
The menu is pretty extensive and has many ‘authentic’ choices- not “dumbed down”. 
There is a Lunch Special menu available Tues-Friday. Specials include 'vegetarian soup' -yes, miso- as well as 'salad', vegetarian egg roll and fried wonton.
On this day, yellow curry with chicken ($11.95) was The Mister's choice. The curries here are very good- there are eight types. Yellow curry is made with potatoes, carrot and onion and coconut milk. A filling, flavorful meal. 
During the pandemic, I would order 'to go' from the appetizer menu. #13, "Crispy Rice Salad" (Nam Kat Tod) has become a favorite. The spicy lime sauce compliments the red and green onion, dry chili flakes, fresh ginger, mint, cilantro and cashews.
All of that is mixed with sour fermented pork (and thinly sliced cartilage) mixed with the crispy rice and toasted rice flour. Very satisfying, especially during our heat wave.
Here is the sushi bar, in its new location. The menu is only sushi; no other Japanese choices.
Thai Thai/Oishii 10251 Mast Blvd Santee, CA 92071 (619) 596-4892 Website Closed Monday, Open Sues-Sun 11-9