Put chicken breasts between 2 sheets of wax paper and pound chicken until slightly flattened. Pour Teriyaki sauce into a sealable plastic bag; add chicken and close bag. Turn bag so that sauce coats each piece of chicken. Refrigerate for 1 hour or as long as 24 hours.

Combine wasabi, sour cream, lemon juice and rind and beat until smooth. Cover and refrigerate until serving time.

Preheat barbecue to medium hot. Mix black and white sesame seeds on a plate. Remove chicken from Teriyaki sauce and throw out the bag. Pat chicken with paper towel to remove extra sauce. Dip each piece in beaten egg then coat with sesame seeds. Trhansferr chicken to a wax paper lined pan and let stand for 10 minutes to allow the coating to set.

Grill for 5-7 minutes per side with the lid down or until a meat thermometer reads 170F (77C). Remove from heat and let stand at room temperature for 5 minutes. Serve with Wasabi Cream Sauce.

Note:
Black sesame seeds are available in Asian grocery stores. Use 1 cup of white sesame seeds if you can't find black ones.