1 small Persian cucumber, seeds removed and julienned
1 teaspoon toasted white sesame seeds
Ponzu sauce, to serve
Tightly line a bamboo mat with plastic wrap.
To prepare lemon: Bring a small sauce pot of water to a boil. Submerge the lemon slices in the water and cook for 2 minutes. Remove into a bowl of ice water to cool completely. Strain the lemon and pat dry with paper towels. Put into the refrigerator until ready to use.
To prepare the rolls: Have the rice, smoked salmon, cream cheese, cucumber and a small bowl of water ready. Place the nori onto the plastic-lined bamboo mat, coarse side up. Spread about 1 cup of sushi rice evenly over the nori, leaving a 1/2-inch border at the top. Dip your hands in the water to prevent the rice from sticking to them.
Sprinkle the rice with 1/2 teaspoon of white sesame seeds. Turn the rice-covered nori sheet over.
Leaving a 1-inch border at the bottom and working your way up, arrange 3 ounces of the smoked salmon in a straight line. Above it, arrange 9 to 12 strips of cucumber. Above the cucumber, spread the cream cheese in a straight line across the nori. Simultaneously fold the nori sheet and bamboo mat tightly over the salmon, cucumber and cream cheese. Press firmly, pulling the mat toward you and shaping into a log. Fold the nori tightly over one more time, and again use the bamboo mat to shape. Remove the bamboo mat.
Top the roll with the blanched lemon slices. Use the bamboo mat to press the lemons into the roll and shape it.
Moisten the blade of a sharp knife. Cut the sushi roll in half, then cut both halves in half. Halve the remaining rolls one more time to yield 8 pieces. Repeat with the remaining nori, rice, smoked salmon, cucumber and cream cheese. Serve with ponzu sauce.