Cut the nori into four narrow strips of equal size. Place one strip of nori on a clean work surface. Place two shiso leaves at one end. Top the leaves with one piece of uni, and roll up in the nori to enclose. Dab the end of the nori with a drop of tempura batter to seal. Repeat the process with the remaining three strips of nori. Coat each roll lightly with flour.
In a deep, heavy pot, heat 2 inches of oil to 350°F. Dip the rolls in the tempura batter to completely coat. Drain off any excess for a couple of seconds, and then fry until crisp, about 3 minutes.
Serve immediately with salt, shichimi, and lime wedges on the side.