A few weeks back, this place opened on the NW corner of Jackson and Kearny in SF Chinatown. They have an extensive selection of noodle and rice dishes, plus other Thai standards, with some unusual menu items that I noted in an earlier post:(http://www.chowhound.com/topics/438828).
I've tried several noodle dishes over the past weeks and have generally been very pleased. It's the best Thai food I've found in the FiDi/Chinatown area, and it now has a permanent place in my lunchtime rotation.
(A side note: for calibration purposes, the rest of my regular lunch rotation includes bun and pho at Golden Flower, salads at Mixt Greens, and the smoked ham rice plate and harvest pork at Henry's Hunan. Once Flying Pan Bistro starts offering take-out, they'll be on the rotation, too. Sam Lok, sadly, has fallen off my regular rounds ever since the dan dan mien debacle a couple of months ago.)
Some general comments on TonYong's food:
Ingredients are fresh, and the cooks are unafraid to make dishes spicy when asked. They're also flexible, giving me the option of Thai basil (bai horapa) or hot/holy basil (bai gaprow) when I asked, and also the option of ground or sliced pork. The one problem -- believe it or not -- is that everything I've tried is undersweetened, and when I say undersweetened, I don't just mean relative to the sickly-sweet style of most American Thai restaurants. I mean undersweetened relative to the gold standards of Thai House Express (SF), Sripriphai (NYC), Lotus of Siam (Vegas), and my somewhat competent home-cooked renditions of Thai food that I learned from Kasma's weeklong intensive course. On every dish I've ordered, I have added sugar. No doubt, better that they undersweeten than oversweeten, and adding sugar is an easy remedy, so it's not a big problem -- it's more that it's really odd.
Pad kee mao: Very spicy as I requested, with a liberal dose of hot basil. Well-balanced flavors once I added my own sugar. I'd prefer the noodles to be both wider and thicker, which might make them stand up better to some real wok-charring, which was missing from the dish, but still quite good.
Macaroni kee mao: Apparently it is common in Thailand to find kee mao made with dried Italian pasta instead of wide fresh rice noodles. I've made it at home with spaghetti and liked it as much as when I used fresh rice noodles. At TonYong, they actually use fusilli, which seemed odd because you lose the fun slippery feeling of oily spaghetti or fresh rice noodles. I preferred the pad kee mao but appreciated the variety.
Pad thai: here the undersweetening was a problem, and I wasn't near a sugar source when I was eating this at my desk. In the Thai course, Kasma taught us how important sugar is to bring out and bring together other flavors, and it's absence here made a difference. Still, the noodles were pleasantly firm, there was no icky ketchup in the sauce, and the balance of salty, sour, and hot (I asked for some spice) was good.
Khao soi: Tried this yellow curry soup with thin fresh egg noodles today. I really liked the creamy, spicy soup, and adding a bit of sugar really brought out the coconut flavor of the thick broth. The noodles were perfectly cooked. They were light on the toppings -- just meat, bean sprouts, and scallon -- and I would have liked more of the crunchy fried onion or garlic bits that khao soi sometimes has. This was perhaps my favorite of the four noodle dishes I've tried.
(khao soi discussion here: http://www.chowhound.com/topics/447845)
Other points about TonYong:
It's small, maybe eight tables, plus some seating upstairs. The space is cramped but sunny. Service is very pleasant. They are fast, and their take-out operation is quite efficient, impressively so for a place that just opened.
Eager to hear other reports.