I couldn't find the PF Chang's Vegetarian Lettuce Wraps but thought this might give you some ideas for the tofu. I will also post the "meat version" lettuce wrap from PF Changs so you can get the flavorings right.
Halyna

Tofu Lettuce Wraps

1 head iceberg lettuce or romaine lettuce leaves
1 Tbsp vegetable oil
1 lb firm Tofu, cut into thin strips
2 scallions, chopped
1 stalk celery, diced
1 can water chestnuts, rinsed and chopped
1 Tbsp minced ginger
1 garlic clove, peeled and minced
1 red bell pepper, seeded and cut into strips

Sauce:
1 Tbsp soy sauce
1 tsp dark sesame oil
2 Tbsp vegetarian oyster sauce
1 Tbsp dry sherry
1 tsp sugar
2 tsp cornstarch
2 Tbsp water

Wash lettuce, and dry gently. Separate the leaves. Set aside.

Mix together the sauce ingredients. Set aside.

In a large frying pan over medium heat, put vegetable oil. Add the garlic, ginger, and green onions and fry 1 minute.

Add Tofu, and cook until lightly browned. Remove from pan, and set aside.

To pan, add bell pepper, water chestnuts, and celery, and stir-fry 3 minutes.

Add Tofu back to pan. Give sauce mixture a stir. Add sauce mixture to pan, and stir-cook until sauce thickens. Remove from heat and keep warm.

To Serve:
Lay out a lettuce leaf on a plate.
Spoon 1 Tbsp filling into middle of lettuce.
Fold up like a taco or burrito, and eat.
Repeat as desired.

VARIATIONS:
Use different vegetables.
Use packaged stir-fry sauce.