Chinese Chicken Salad Sandwich

Ingredients

1/4 cup soy sauce
1/4 cup rice wine vinegar
1/4 cup vegetable or peanut oil
1/4 cup roasted sesame seed oil
2 tablespoons fresh ginger root, minced
4 teaspoons sugar
4 teaspoons dry mustard
2 pounds chicken breast, boned, skinned, steamed and cubed
1 large red onion (about 9 to 11 ounces), cut into narrow wedges
1 cup pea pods, fresh or thawed frozen, slivered
6 crusty round rolls, split, buttered
Lettuce or watercress
4 teaspoons sesame seeds, toasted