I really love Lao Sze Chuan. It's some of the finest Chinese food I've ever eaten and a godsend for anyone in the greater New Haven area.
First and foremost, make sure to order the "bamboo in wild pepper sauce" appetizer ($7). This by far is my favorite dish on the menu. The dish consists of tender bamboo stalks covered in sesame seeds and a special Szechuan peppercorn and chili sauce available only in this dish. It's savory and spicy, but in an unusual, refreshing way: it numbs your tongue a bit and actually cleanses your palate. If you've never had Szechuan peppercorn, this is a lovely introduction to a taste you won't find anywhere else.
The vegetable dumplings ($6) are also excellent, with homemade dough wrapped around an array of diced and spiced vegetables.
For entrees, the vegetarian mapo tofu ($10) is always a solid choice of hearty, savory food (it's Chinese soulfood); the shredded potato with green pepper is also excellent and down-home, cooked in a delicious garlic sauce ($10). Similarly, the mixed vegetables ($10) can be made with a fermented black bean sauce and the results are wonderful.
However, I'd skip the Chinese eggplant ($10) and some of the more basic-sounding vegetable dishes (stir-fried cabbage, stir-fried spinach) because, while they might be tasty, they're overly basic; you'll get a plate of leaves and a few red chilis in the mix, but nothing else.
Amazingly, Lao Sze Chuan offers brown rice which is an awesome touch and makes coming here all the more enjoyable (I hate getting served white rice with food as complex and delectable as this).
The service is always friendly and helpful. Be warned that the restaurant gets really crowded particularly on Friday and Saturday nights. If you're coming with a group of more than four, definitely make a reservation.
Lao Sze Chuan is definitely a winner and I'd come back for the bamboo in wild pepper dish if nothing else. If they had a few more interesting tofu dishes or more interesting vegetable options, I'd give them five stars.