I couldn't find Pei Wei's version on the Internet. Pei Wei is owned by PF Chang's. Perhaps you could work from this recipe. Good luck.
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P.F. CHANG'S HOT AND SOUR SOUP
Source; P.F. Chang's
From: KOTV, Channel 6, Tulsa, OK
Thursday, January 01, 2004

1 quart chicken stock
1 C. soy sauce
1 tsp. white pepper
6 oz. bamboo strips
6 oz. woodear mushrooms
6 oz. chicken breast cut into strips
1 C. slurry (1/2 corn starch, 1/2 water)
2 eggs, beaten
4 oz. white vinegar
6 oz. silken tofu cut into strips

Bring stock to boil. Add soy sauce, white pepper, bamboo, mushrooms and chicken. Let cook for 3 minutes. Add slurry a little at a time and stir until thick (all slurry may not be necessary). Add eggs and cook for 30 seconds or until eggs are done. Turn off fire. Add vinegar and tofu in a bowl and pour soup on top. Stir and eat.