Arrange KA–ME Seaweed Rice Crackers on a serving plate.
Cut tuna into four lengthwise pieces. Pour KA–ME 100% Pure Sesame Oil over tuna (reserving 2 tbsp.); turn to coat evenly. Mix black and white sesame seeds, pepper and salt on large plate. Coat tuna with sesame seed mixture, pressing firmly so mixture adheres to the tuna.
Heat reserved 2 tbsp oil in large skillet on high heat. Add tuna; sear 2 minutes per side. Remove from skillet; set aside to cool.
Mix KA–ME Hot Mustard and KA–ME Tamari in small bowl until blended, set aside.
Slice tuna into 1/8-inch thick slices. Place 1 slice of tuna on each Rice Cracker.
Top each with a small dollop of Hot Mustard and Tamari mixture.