In a medium bowl combine lemon juice, mirin, soy sauce, wasabi paste, and whisk thoroughly. Set it aside in the refrigerator. Parchment paper line a sheet pan then place a cooling rack on top and set aside.
Peel sweet potato and slice ¼ inch (6 millimeter) thick.
Peel and deveined the shrimp if needed. (Note: You can cut 2 or 3 (1/8 inch) slits along center (belly) of shrimp slightly giving it illusion of length). Pat shrimps dry with paper towel to absorb any excessive liquids.
Add oil to a large pot, (should be leveled at 1 ½ inches from bottom of pot). Heat the oil to 350° F degrees.
In a medium size bowl add eggs and lightly beat them for 5 seconds. Then add club soda.
Next add flour to egg mixture and mix until fully incorporated (batter will have small lumps). Do for about 1 minutes so as not to over mix.
Drop a few sweet potato slices into the batter, cover thoroughly. Delicately lower individually battered sweet potato slice into hot oil and cook for 1 minutes on each side. Remove sweet potato slice from oil using fryer ladle, place them on cooling rack you reserved earlier in Step 1.
Gripping shrimp tail, dip it into the batter, covering thoroughly. Delicately lower battered shrimp into hot oil and cook for 2 minutes on each side. Remove shrimp from oil using fryer ladle, place them on cooling rack you reserved earlier in Step 1.
Arrange the tempura shrimp and veggies on a serving platter. Warm dipping sauce on stovetop for 1 minute or microwave for 30 seconds, before serving in preferred warm dish with shrimp and veggies.