Ice Cream: Bring milk to simmer in small saucepan on medium heat. Remove from heat. Stir in tea leaves. Let steep 4 min. Strain milk into clean medium saucepan, pressing tea leaves to extract maximum flavor. Discard tea leaves.
Whisk egg yolks and 1 oz. sugar in small bowl. Stir in a small amount of the milk mixture; set aside.
Stir condensed milk and heavy cream into remaining milk mixture in saucepan. Combine remaining sugar, nonfat dry milk, dextrose and ice cream stabilizer in small bowl; add to saucepan. Whisk until well blended. Bring to simmer on medium heat. Stir small amount of warm cream mixture into egg yolk mixture; return to saucepan. Cook on low heat, stirring constantly, until mixture reaches 165°F. Remove from heat; strain.
Pour small amounts of mixture into blender and process 30 seconds. Transfer to clean bowl and chill over an ice bath. Continue until all of mixture has been processed. Refrigerate overnight.
Freeze mixture in ice cream maker according to manufacturer's directions. Spoon prepared ice cream into freezer container. Gently fold in OREO Pieces. Freeze until firm.
Using #40 scoop, portion 14 scoops ice cream onto parchment paper-lined quarter sheet pan; flatten slightly. Freeze until solid. (Each scoop should weigh 1.15 oz.)
Mochi: Combine sugar, rice powder and cocoa in microwaveable bowl. Whisk in water until mixture is smooth. Cover loosely with plastic wrap. Microwave on HIGH 5 min., stirring after each minute.
Sift cornstarch onto silicone baking mat. Pour warm sugar mixture onto cornstarch. Sift additional cornstarch over top. Press to flatten, using caution as mixture is hot. Let cool until dough can be handled. Flip dough over on pan.
Roll out dough to 1/8th-inch thick, adding more cornstarch as needed to prevent sticking. Use 4-1/8th-inch round cutter to cut out 14 circles. (Each circle should weigh 1.15 oz.) Layer circles between parchment paper and refrigerate 30 min. or until firm.
To assemble, place 1 mochi circle on 9x9-inch square of plastic wrap. Top with 1 flattened ice cream scoop. Fold dough up and around ice cream, using water as needed to help mochi stick to itself. Wrap plastic tightly around filled mochi, twisting at base. Repeat with remaining mochi circles and ice cream. Freeze until solid.